<?xml version="1.0" encoding="UTF-8"?>

<!--XBRL Document Created with the Workiva Platform-->
<!--Copyright 2024 Workiva-->
<!--r:65629827-4189-4509-8f99-52a9a4cba686,g:cbb6b131-d2fa-4b56-bca0-272c967ff750-->
<link:linkbase xmlns:link="http://www.xbrl.org/2003/linkbase" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xbrldt="http://xbrl.org/2005/xbrldt" xsi:schemaLocation="http://www.xbrl.org/2003/linkbase http://www.xbrl.org/2003/xbrl-linkbase-2003-12-31.xsd">
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/all" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#all"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#hypercube-dimension"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-default"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-domain"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/domain-member" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#domain-member"/>
  <link:roleRef roleURI="http://www.blackbaud.com/role/Document" xlink:type="simple" xlink:href="blkb-20240930.xsd#Document"/>
  <link:definitionLink xlink:role="http://www.blackbaud.com/role/Document" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_dei_DocumentInformationLineItems_a4c0f4b8-17d1-41fc-946a-cd42d4a53111" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_DocumentInformationLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_DocumentInformationTable_787d38a6-e34d-40e7-b0f2-16e80aec2019" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_DocumentInformationTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_dei_DocumentInformationLineItems_a4c0f4b8-17d1-41fc-946a-cd42d4a53111" xlink:to="loc_dei_DocumentInformationTable_787d38a6-e34d-40e7-b0f2-16e80aec2019" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementClassOfStockAxis_c47dd73f-04a7-4cc7-a5cb-b00293a0b262" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StatementClassOfStockAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_dei_DocumentInformationTable_787d38a6-e34d-40e7-b0f2-16e80aec2019" xlink:to="loc_us-gaap_StatementClassOfStockAxis_c47dd73f-04a7-4cc7-a5cb-b00293a0b262" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_c47dd73f-04a7-4cc7-a5cb-b00293a0b262_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementClassOfStockAxis_c47dd73f-04a7-4cc7-a5cb-b00293a0b262" xlink:to="loc_us-gaap_ClassOfStockDomain_c47dd73f-04a7-4cc7-a5cb-b00293a0b262_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockDomain_f6fcb216-9f7a-480d-8d7c-8a7bbdb88825" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ClassOfStockDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis_c47dd73f-04a7-4cc7-a5cb-b00293a0b262" xlink:to="loc_us-gaap_ClassOfStockDomain_f6fcb216-9f7a-480d-8d7c-8a7bbdb88825" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_DocumentType_223e70ba-921a-4f0a-bf34-8f64a130a90f" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_DocumentType"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_a4c0f4b8-17d1-41fc-946a-cd42d4a53111" xlink:to="loc_dei_DocumentType_223e70ba-921a-4f0a-bf34-8f64a130a90f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_DocumentQuarterlyReport_0a00740e-6571-423c-9a8a-6a2f1f878d69" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_DocumentQuarterlyReport"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_a4c0f4b8-17d1-41fc-946a-cd42d4a53111" xlink:to="loc_dei_DocumentQuarterlyReport_0a00740e-6571-423c-9a8a-6a2f1f878d69" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_DocumentPeriodEndDate_cb939cb5-fa02-4941-a079-50be64f0a02d" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_DocumentPeriodEndDate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_a4c0f4b8-17d1-41fc-946a-cd42d4a53111" xlink:to="loc_dei_DocumentPeriodEndDate_cb939cb5-fa02-4941-a079-50be64f0a02d" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_DocumentTransitionReport_8311112b-76a8-4f8e-8912-f237596471b5" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_DocumentTransitionReport"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_a4c0f4b8-17d1-41fc-946a-cd42d4a53111" xlink:to="loc_dei_DocumentTransitionReport_8311112b-76a8-4f8e-8912-f237596471b5" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityFileNumber_1e8acc7e-d561-4dd0-82ce-bd80d88931ef" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_EntityFileNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_a4c0f4b8-17d1-41fc-946a-cd42d4a53111" xlink:to="loc_dei_EntityFileNumber_1e8acc7e-d561-4dd0-82ce-bd80d88931ef" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityRegistrantName_0193c970-8359-4f39-bdec-5139833117e3" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_EntityRegistrantName"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_a4c0f4b8-17d1-41fc-946a-cd42d4a53111" xlink:to="loc_dei_EntityRegistrantName_0193c970-8359-4f39-bdec-5139833117e3" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityIncorporationStateCountryCode_bb2d5148-2a9b-49db-8acc-68f5c4132b5a" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_EntityIncorporationStateCountryCode"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_a4c0f4b8-17d1-41fc-946a-cd42d4a53111" xlink:to="loc_dei_EntityIncorporationStateCountryCode_bb2d5148-2a9b-49db-8acc-68f5c4132b5a" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityTaxIdentificationNumber_341a8527-1fda-4c94-afe0-119ca378d9c8" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_EntityTaxIdentificationNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_a4c0f4b8-17d1-41fc-946a-cd42d4a53111" xlink:to="loc_dei_EntityTaxIdentificationNumber_341a8527-1fda-4c94-afe0-119ca378d9c8" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityAddressAddressLine1_f9664567-2805-45ea-93eb-031bdd90b780" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_EntityAddressAddressLine1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_a4c0f4b8-17d1-41fc-946a-cd42d4a53111" xlink:to="loc_dei_EntityAddressAddressLine1_f9664567-2805-45ea-93eb-031bdd90b780" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityAddressCityOrTown_c362520a-800f-46b2-8cc3-1a3c47f539cf" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_EntityAddressCityOrTown"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_a4c0f4b8-17d1-41fc-946a-cd42d4a53111" xlink:to="loc_dei_EntityAddressCityOrTown_c362520a-800f-46b2-8cc3-1a3c47f539cf" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityAddressStateOrProvince_33fa8f90-ad96-4c19-8d19-dcbecb6d7809" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_EntityAddressStateOrProvince"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_a4c0f4b8-17d1-41fc-946a-cd42d4a53111" xlink:to="loc_dei_EntityAddressStateOrProvince_33fa8f90-ad96-4c19-8d19-dcbecb6d7809" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityAddressPostalZipCode_de0d7e39-ac3a-48d4-a833-45394fcdccc6" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_EntityAddressPostalZipCode"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_a4c0f4b8-17d1-41fc-946a-cd42d4a53111" xlink:to="loc_dei_EntityAddressPostalZipCode_de0d7e39-ac3a-48d4-a833-45394fcdccc6" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_CityAreaCode_4599787d-7997-4eb8-8db9-76623f329dd1" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_CityAreaCode"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_a4c0f4b8-17d1-41fc-946a-cd42d4a53111" xlink:to="loc_dei_CityAreaCode_4599787d-7997-4eb8-8db9-76623f329dd1" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_LocalPhoneNumber_d36c3186-19c6-4d33-a72e-4f5693f61540" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_LocalPhoneNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_a4c0f4b8-17d1-41fc-946a-cd42d4a53111" xlink:to="loc_dei_LocalPhoneNumber_d36c3186-19c6-4d33-a72e-4f5693f61540" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_Security12bTitle_dde7eabf-6842-4061-91d3-6ee1bdc8edd9" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_Security12bTitle"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_a4c0f4b8-17d1-41fc-946a-cd42d4a53111" xlink:to="loc_dei_Security12bTitle_dde7eabf-6842-4061-91d3-6ee1bdc8edd9" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_TradingSymbol_976f5541-5adb-4abf-847c-994b800f922b" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_TradingSymbol"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_a4c0f4b8-17d1-41fc-946a-cd42d4a53111" xlink:to="loc_dei_TradingSymbol_976f5541-5adb-4abf-847c-994b800f922b" xlink:type="arc" order="15"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_SecurityExchangeName_f200f274-b4dc-4173-b5d0-7a4ddff0e88e" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_SecurityExchangeName"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_a4c0f4b8-17d1-41fc-946a-cd42d4a53111" xlink:to="loc_dei_SecurityExchangeName_f200f274-b4dc-4173-b5d0-7a4ddff0e88e" xlink:type="arc" order="16"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityCurrentReportingStatus_d0b4aca3-2003-4828-9c7c-60c922cc92d5" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_EntityCurrentReportingStatus"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_a4c0f4b8-17d1-41fc-946a-cd42d4a53111" xlink:to="loc_dei_EntityCurrentReportingStatus_d0b4aca3-2003-4828-9c7c-60c922cc92d5" xlink:type="arc" order="17"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityInteractiveDataCurrent_71c68467-89e0-4819-ac45-e72f805edd73" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_EntityInteractiveDataCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_a4c0f4b8-17d1-41fc-946a-cd42d4a53111" xlink:to="loc_dei_EntityInteractiveDataCurrent_71c68467-89e0-4819-ac45-e72f805edd73" xlink:type="arc" order="18"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityFilerCategory_87c8dbb7-9e49-488f-90eb-bc93d742e56d" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_EntityFilerCategory"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_a4c0f4b8-17d1-41fc-946a-cd42d4a53111" xlink:to="loc_dei_EntityFilerCategory_87c8dbb7-9e49-488f-90eb-bc93d742e56d" xlink:type="arc" order="19"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntitySmallBusiness_e10d51ad-d64a-4ff8-b684-fcad48ecf59a" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_EntitySmallBusiness"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_a4c0f4b8-17d1-41fc-946a-cd42d4a53111" xlink:to="loc_dei_EntitySmallBusiness_e10d51ad-d64a-4ff8-b684-fcad48ecf59a" xlink:type="arc" order="20"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityEmergingGrowthCompany_dd1bf81a-4f75-4951-9131-5649cfcf7de2" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_EntityEmergingGrowthCompany"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_a4c0f4b8-17d1-41fc-946a-cd42d4a53111" xlink:to="loc_dei_EntityEmergingGrowthCompany_dd1bf81a-4f75-4951-9131-5649cfcf7de2" xlink:type="arc" order="21"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityShellCompany_225670cd-5c64-47c4-9028-8313236c4a4e" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_EntityShellCompany"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_a4c0f4b8-17d1-41fc-946a-cd42d4a53111" xlink:to="loc_dei_EntityShellCompany_225670cd-5c64-47c4-9028-8313236c4a4e" xlink:type="arc" order="22"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityCommonStockSharesOutstanding_44b2d561-34ba-437a-8b1d-7672f8c97acd" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_EntityCommonStockSharesOutstanding"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_a4c0f4b8-17d1-41fc-946a-cd42d4a53111" xlink:to="loc_dei_EntityCommonStockSharesOutstanding_44b2d561-34ba-437a-8b1d-7672f8c97acd" xlink:type="arc" order="23"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_AmendmentFlag_52f76acd-08c3-4431-9e5b-50f9f5a3da27" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_AmendmentFlag"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_a4c0f4b8-17d1-41fc-946a-cd42d4a53111" xlink:to="loc_dei_AmendmentFlag_52f76acd-08c3-4431-9e5b-50f9f5a3da27" xlink:type="arc" order="24"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_DocumentFiscalYearFocus_4826ba43-f1d1-4c5d-a6d8-1b58050e3235" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_DocumentFiscalYearFocus"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_a4c0f4b8-17d1-41fc-946a-cd42d4a53111" xlink:to="loc_dei_DocumentFiscalYearFocus_4826ba43-f1d1-4c5d-a6d8-1b58050e3235" xlink:type="arc" order="25"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_DocumentFiscalPeriodFocus_9df564ed-24b5-407e-ac17-05677a1ca486" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_DocumentFiscalPeriodFocus"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_a4c0f4b8-17d1-41fc-946a-cd42d4a53111" xlink:to="loc_dei_DocumentFiscalPeriodFocus_9df564ed-24b5-407e-ac17-05677a1ca486" xlink:type="arc" order="26"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityCentralIndexKey_3bc555bc-fd7e-42aa-92e9-51a81cc2a872" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_EntityCentralIndexKey"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_a4c0f4b8-17d1-41fc-946a-cd42d4a53111" xlink:to="loc_dei_EntityCentralIndexKey_3bc555bc-fd7e-42aa-92e9-51a81cc2a872" xlink:type="arc" order="27"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_CurrentFiscalYearEndDate_c8bbcf09-9e62-4a2f-9efc-8e2288ef1028" xlink:href="https://xbrl.sec.gov/dei/2024/dei-2024.xsd#dei_CurrentFiscalYearEndDate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_DocumentInformationLineItems_a4c0f4b8-17d1-41fc-946a-cd42d4a53111" xlink:to="loc_dei_CurrentFiscalYearEndDate_c8bbcf09-9e62-4a2f-9efc-8e2288ef1028" xlink:type="arc" order="28"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.blackbaud.com/role/CondensedConsolidatedStatementsofComprehensiveIncome" xlink:type="simple" xlink:href="blkb-20240930.xsd#CondensedConsolidatedStatementsofComprehensiveIncome"/>
  <link:definitionLink xlink:role="http://www.blackbaud.com/role/CondensedConsolidatedStatementsofComprehensiveIncome" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementLineItems_f9c048c1-5bf5-40ce-8eee-6a8a757f366f" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StatementLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementTable_1ceb7e1a-af19-4c24-981c-56675ca9916c" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StatementTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_f9c048c1-5bf5-40ce-8eee-6a8a757f366f" xlink:to="loc_us-gaap_StatementTable_1ceb7e1a-af19-4c24-981c-56675ca9916c" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductOrServiceAxis_cd31fce4-1796-4138-86d0-8b8ddd4b481b" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_ProductOrServiceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_1ceb7e1a-af19-4c24-981c-56675ca9916c" xlink:to="loc_srt_ProductOrServiceAxis_cd31fce4-1796-4138-86d0-8b8ddd4b481b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_cd31fce4-1796-4138-86d0-8b8ddd4b481b_default" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ProductOrServiceAxis_cd31fce4-1796-4138-86d0-8b8ddd4b481b" xlink:to="loc_srt_ProductsAndServicesDomain_cd31fce4-1796-4138-86d0-8b8ddd4b481b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_a081d157-722c-4ca9-a843-9ded7c18dd72" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ProductOrServiceAxis_cd31fce4-1796-4138-86d0-8b8ddd4b481b" xlink:to="loc_srt_ProductsAndServicesDomain_a081d157-722c-4ca9-a843-9ded7c18dd72" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_blkb_RecurringMember_58638069-a445-46b3-bdf3-596db167cddd" xlink:href="blkb-20240930.xsd#blkb_RecurringMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_a081d157-722c-4ca9-a843-9ded7c18dd72" xlink:to="loc_blkb_RecurringMember_58638069-a445-46b3-bdf3-596db167cddd" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TechnologyServiceMember_a9ef1d8d-0766-465e-a87a-bd398c6ab78d" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_TechnologyServiceMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_a081d157-722c-4ca9-a843-9ded7c18dd72" xlink:to="loc_us-gaap_TechnologyServiceMember_a9ef1d8d-0766-465e-a87a-bd398c6ab78d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenuesAbstract_9c3a1fbd-da03-4136-868a-0c3b0af9f9f7" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RevenuesAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_f9c048c1-5bf5-40ce-8eee-6a8a757f366f" xlink:to="loc_us-gaap_RevenuesAbstract_9c3a1fbd-da03-4136-868a-0c3b0af9f9f7" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_7624146e-c683-4037-8906-3e22dcbabecf" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenuesAbstract_9c3a1fbd-da03-4136-868a-0c3b0af9f9f7" xlink:to="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_7624146e-c683-4037-8906-3e22dcbabecf" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CostOfRevenueAbstract_95e8ba39-e32f-45a1-8de0-8f0c4698114c" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CostOfRevenueAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_f9c048c1-5bf5-40ce-8eee-6a8a757f366f" xlink:to="loc_us-gaap_CostOfRevenueAbstract_95e8ba39-e32f-45a1-8de0-8f0c4698114c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CostOfGoodsAndServicesSold_61e2d0d7-f24f-4800-ba4d-f42a20b3ede2" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CostOfGoodsAndServicesSold"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CostOfRevenueAbstract_95e8ba39-e32f-45a1-8de0-8f0c4698114c" xlink:to="loc_us-gaap_CostOfGoodsAndServicesSold_61e2d0d7-f24f-4800-ba4d-f42a20b3ede2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GrossProfit_a9238d9c-6da4-477b-b8e6-ce16a587e5cd" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_GrossProfit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_f9c048c1-5bf5-40ce-8eee-6a8a757f366f" xlink:to="loc_us-gaap_GrossProfit_a9238d9c-6da4-477b-b8e6-ce16a587e5cd" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingExpensesAbstract_68a71094-084a-4816-8274-f554312c21b4" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_OperatingExpensesAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_f9c048c1-5bf5-40ce-8eee-6a8a757f366f" xlink:to="loc_us-gaap_OperatingExpensesAbstract_68a71094-084a-4816-8274-f554312c21b4" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SellingAndMarketingExpense_2165b236-600c-4bc6-88d6-eeb34f3bcede" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SellingAndMarketingExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingExpensesAbstract_68a71094-084a-4816-8274-f554312c21b4" xlink:to="loc_us-gaap_SellingAndMarketingExpense_2165b236-600c-4bc6-88d6-eeb34f3bcede" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ResearchAndDevelopmentExpense_9daa588b-c503-4ec2-abe7-c2a6cbc96b12" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ResearchAndDevelopmentExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingExpensesAbstract_68a71094-084a-4816-8274-f554312c21b4" xlink:to="loc_us-gaap_ResearchAndDevelopmentExpense_9daa588b-c503-4ec2-abe7-c2a6cbc96b12" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GeneralAndAdministrativeExpense_3468711f-cd13-49a1-b709-66afb1291b5c" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_GeneralAndAdministrativeExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingExpensesAbstract_68a71094-084a-4816-8274-f554312c21b4" xlink:to="loc_us-gaap_GeneralAndAdministrativeExpense_3468711f-cd13-49a1-b709-66afb1291b5c" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AmortizationOfIntangibleAssets_8bb6fee2-df8c-481b-adf0-3bfc674f9860" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AmortizationOfIntangibleAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingExpensesAbstract_68a71094-084a-4816-8274-f554312c21b4" xlink:to="loc_us-gaap_AmortizationOfIntangibleAssets_8bb6fee2-df8c-481b-adf0-3bfc674f9860" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingExpenses_8ab58264-49c2-4c91-9181-a8f8a460efbd" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_OperatingExpenses"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingExpensesAbstract_68a71094-084a-4816-8274-f554312c21b4" xlink:to="loc_us-gaap_OperatingExpenses_8ab58264-49c2-4c91-9181-a8f8a460efbd" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingIncomeLoss_3ea6e6a2-d344-4cff-9763-b5baed987ede" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_OperatingIncomeLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_f9c048c1-5bf5-40ce-8eee-6a8a757f366f" xlink:to="loc_us-gaap_OperatingIncomeLoss_3ea6e6a2-d344-4cff-9763-b5baed987ede" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestExpense_aaf81cb5-fa7e-4a64-8522-0942f32e92a3" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_InterestExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_f9c048c1-5bf5-40ce-8eee-6a8a757f366f" xlink:to="loc_us-gaap_InterestExpense_aaf81cb5-fa7e-4a64-8522-0942f32e92a3" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_blkb_NonoperatingIncomeExpenseExcludingInterestExpense_6bd16f47-9ea1-4001-a4ee-5a80e083b3aa" xlink:href="blkb-20240930.xsd#blkb_NonoperatingIncomeExpenseExcludingInterestExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_f9c048c1-5bf5-40ce-8eee-6a8a757f366f" xlink:to="loc_blkb_NonoperatingIncomeExpenseExcludingInterestExpense_6bd16f47-9ea1-4001-a4ee-5a80e083b3aa" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest_2070ab49-a3f2-4ff4-bec9-41187137a055" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_f9c048c1-5bf5-40ce-8eee-6a8a757f366f" xlink:to="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest_2070ab49-a3f2-4ff4-bec9-41187137a055" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxExpenseBenefit_41f4dd56-1da6-42c4-94fc-0e9991704dbb" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_IncomeTaxExpenseBenefit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_f9c048c1-5bf5-40ce-8eee-6a8a757f366f" xlink:to="loc_us-gaap_IncomeTaxExpenseBenefit_41f4dd56-1da6-42c4-94fc-0e9991704dbb" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLoss_48eb3b0d-c180-4691-9ff5-c808aebaac5a" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_NetIncomeLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_f9c048c1-5bf5-40ce-8eee-6a8a757f366f" xlink:to="loc_us-gaap_NetIncomeLoss_48eb3b0d-c180-4691-9ff5-c808aebaac5a" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EarningsPerShareAbstract_465974c8-1e6c-445a-b8b0-5f40d8f60dd0" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_EarningsPerShareAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_f9c048c1-5bf5-40ce-8eee-6a8a757f366f" xlink:to="loc_us-gaap_EarningsPerShareAbstract_465974c8-1e6c-445a-b8b0-5f40d8f60dd0" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EarningsPerShareBasic_700959a7-83a2-4d61-9aae-05a033ff190b" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_EarningsPerShareBasic"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EarningsPerShareAbstract_465974c8-1e6c-445a-b8b0-5f40d8f60dd0" xlink:to="loc_us-gaap_EarningsPerShareBasic_700959a7-83a2-4d61-9aae-05a033ff190b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EarningsPerShareDiluted_f761ab12-a239-4651-8368-0d3ae3b52cf4" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_EarningsPerShareDiluted"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EarningsPerShareAbstract_465974c8-1e6c-445a-b8b0-5f40d8f60dd0" xlink:to="loc_us-gaap_EarningsPerShareDiluted_f761ab12-a239-4651-8368-0d3ae3b52cf4" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingAbstract_5bf6c219-d6a2-441a-acf7-89617ab49b05" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_WeightedAverageNumberOfSharesOutstandingAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_f9c048c1-5bf5-40ce-8eee-6a8a757f366f" xlink:to="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingAbstract_5bf6c219-d6a2-441a-acf7-89617ab49b05" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_02a208cb-1197-4dd6-b0f9-4f0d8fbfec5d" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_WeightedAverageNumberOfSharesOutstandingBasic"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingAbstract_5bf6c219-d6a2-441a-acf7-89617ab49b05" xlink:to="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_02a208cb-1197-4dd6-b0f9-4f0d8fbfec5d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding_c13511e1-d93c-40dc-9b54-f61598c9ab14" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingAbstract_5bf6c219-d6a2-441a-acf7-89617ab49b05" xlink:to="loc_us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding_c13511e1-d93c-40dc-9b54-f61598c9ab14" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTaxPeriodIncreaseDecreaseAbstract_aa17f579-39d6-47de-8fe7-fc5c75c5649b" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_OtherComprehensiveIncomeLossNetOfTaxPeriodIncreaseDecreaseAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_f9c048c1-5bf5-40ce-8eee-6a8a757f366f" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTaxPeriodIncreaseDecreaseAbstract_aa17f579-39d6-47de-8fe7-fc5c75c5649b" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossForeignCurrencyTransactionAndTranslationAdjustmentNetOfTax_e155b632-57cf-4df1-86f9-8b21f7d5ea6e" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_OtherComprehensiveIncomeLossForeignCurrencyTransactionAndTranslationAdjustmentNetOfTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTaxPeriodIncreaseDecreaseAbstract_aa17f579-39d6-47de-8fe7-fc5c75c5649b" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossForeignCurrencyTransactionAndTranslationAdjustmentNetOfTax_e155b632-57cf-4df1-86f9-8b21f7d5ea6e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossAfterReclassificationAndTaxParent_dc71eba6-27ec-44be-9a82-da7d9ab05b2d" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossAfterReclassificationAndTaxParent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTaxPeriodIncreaseDecreaseAbstract_aa17f579-39d6-47de-8fe7-fc5c75c5649b" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossAfterReclassificationAndTaxParent_dc71eba6-27ec-44be-9a82-da7d9ab05b2d" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent_3e990ff2-6c9d-4bc4-873f-6a16f179df82" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTaxPeriodIncreaseDecreaseAbstract_aa17f579-39d6-47de-8fe7-fc5c75c5649b" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent_3e990ff2-6c9d-4bc4-873f-6a16f179df82" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ComprehensiveIncomeNetOfTax_1500316c-c193-488f-97b2-0152149d9a6c" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ComprehensiveIncomeNetOfTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_f9c048c1-5bf5-40ce-8eee-6a8a757f366f" xlink:to="loc_us-gaap_ComprehensiveIncomeNetOfTax_1500316c-c193-488f-97b2-0152149d9a6c" xlink:type="arc" order="13"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.blackbaud.com/role/CondensedConsolidatedStatementsofStockholdersEquity" xlink:type="simple" xlink:href="blkb-20240930.xsd#CondensedConsolidatedStatementsofStockholdersEquity"/>
  <link:definitionLink xlink:role="http://www.blackbaud.com/role/CondensedConsolidatedStatementsofStockholdersEquity" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementLineItems_c615e495-4da4-4177-885c-c4f3eb8de670" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StatementLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementTable_e9900288-102c-4951-90e2-bab9521c3e53" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StatementTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_c615e495-4da4-4177-885c-c4f3eb8de670" xlink:to="loc_us-gaap_StatementTable_e9900288-102c-4951-90e2-bab9521c3e53" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementEquityComponentsAxis_48e40c04-8252-4307-83d7-d06c9285ed9e" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StatementEquityComponentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_e9900288-102c-4951-90e2-bab9521c3e53" xlink:to="loc_us-gaap_StatementEquityComponentsAxis_48e40c04-8252-4307-83d7-d06c9285ed9e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_48e40c04-8252-4307-83d7-d06c9285ed9e_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_48e40c04-8252-4307-83d7-d06c9285ed9e" xlink:to="loc_us-gaap_EquityComponentDomain_48e40c04-8252-4307-83d7-d06c9285ed9e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_935e8102-7992-4c45-b115-e28134de21d4" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_48e40c04-8252-4307-83d7-d06c9285ed9e" xlink:to="loc_us-gaap_EquityComponentDomain_935e8102-7992-4c45-b115-e28134de21d4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockMember_177d6d29-a7e3-43c8-8d0e-447db61da3c4" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CommonStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_935e8102-7992-4c45-b115-e28134de21d4" xlink:to="loc_us-gaap_CommonStockMember_177d6d29-a7e3-43c8-8d0e-447db61da3c4" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TreasuryStockCommonMember_1f0edf0f-938c-46df-a3ee-5cafe9f438e7" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_TreasuryStockCommonMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_935e8102-7992-4c45-b115-e28134de21d4" xlink:to="loc_us-gaap_TreasuryStockCommonMember_1f0edf0f-938c-46df-a3ee-5cafe9f438e7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdditionalPaidInCapitalMember_ed558150-893c-4f93-81df-383e69a5c579" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AdditionalPaidInCapitalMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_935e8102-7992-4c45-b115-e28134de21d4" xlink:to="loc_us-gaap_AdditionalPaidInCapitalMember_ed558150-893c-4f93-81df-383e69a5c579" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_394dbee4-bc0d-45ca-9d15-47dbea2e7391" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_935e8102-7992-4c45-b115-e28134de21d4" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_394dbee4-bc0d-45ca-9d15-47dbea2e7391" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetainedEarningsMember_c1a9bf83-9f5b-46ee-8c99-c5b374ae93b0" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RetainedEarningsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_935e8102-7992-4c45-b115-e28134de21d4" xlink:to="loc_us-gaap_RetainedEarningsMember_c1a9bf83-9f5b-46ee-8c99-c5b374ae93b0" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_cbfb17c1-3728-4988-9ac8-13b24968335f" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_IncreaseDecreaseInStockholdersEquityRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_c615e495-4da4-4177-885c-c4f3eb8de670" xlink:to="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_cbfb17c1-3728-4988-9ac8-13b24968335f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharesIssued_2971372c-7a61-4f8a-9c73-6940ecd0fd0a" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SharesIssued"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_cbfb17c1-3728-4988-9ac8-13b24968335f" xlink:to="loc_us-gaap_SharesIssued_2971372c-7a61-4f8a-9c73-6940ecd0fd0a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquity_5684d7e8-59e9-4197-933e-dc7fe1160448" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StockholdersEquity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_cbfb17c1-3728-4988-9ac8-13b24968335f" xlink:to="loc_us-gaap_StockholdersEquity_5684d7e8-59e9-4197-933e-dc7fe1160448" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TreasuryStockCommonShares_f7eca61a-1d7c-4ea9-b6f2-faf92e0cd757" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_TreasuryStockCommonShares"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_cbfb17c1-3728-4988-9ac8-13b24968335f" xlink:to="loc_us-gaap_TreasuryStockCommonShares_f7eca61a-1d7c-4ea9-b6f2-faf92e0cd757" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLoss_e728ba9f-6281-4bab-b26f-8ecbe98813d5" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_NetIncomeLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_cbfb17c1-3728-4988-9ac8-13b24968335f" xlink:to="loc_us-gaap_NetIncomeLoss_e728ba9f-6281-4bab-b26f-8ecbe98813d5" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_blkb_RetirementsOfCommonStockShares_15a79445-1b5c-4b44-9a00-05d830c47e54" xlink:href="blkb-20240930.xsd#blkb_RetirementsOfCommonStockShares"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_cbfb17c1-3728-4988-9ac8-13b24968335f" xlink:to="loc_blkb_RetirementsOfCommonStockShares_15a79445-1b5c-4b44-9a00-05d830c47e54" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_blkb_AdjustmentsToAdditionalPaidInCapitalStockIssuedRetirements_c67c6f2d-0c55-4c83-8ba4-8c26e7f80e43" xlink:href="blkb-20240930.xsd#blkb_AdjustmentsToAdditionalPaidInCapitalStockIssuedRetirements"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_cbfb17c1-3728-4988-9ac8-13b24968335f" xlink:to="loc_blkb_AdjustmentsToAdditionalPaidInCapitalStockIssuedRetirements_c67c6f2d-0c55-4c83-8ba4-8c26e7f80e43" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TreasuryStockSharesAcquired_e605fb52-9cfa-4e60-8b3c-0ffa06b42c62" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_TreasuryStockSharesAcquired"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_cbfb17c1-3728-4988-9ac8-13b24968335f" xlink:to="loc_us-gaap_TreasuryStockSharesAcquired_e605fb52-9cfa-4e60-8b3c-0ffa06b42c62" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TreasuryStockValueAcquiredCostMethod_047c19a8-db04-445b-a106-1e68d628d57f" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_TreasuryStockValueAcquiredCostMethod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_cbfb17c1-3728-4988-9ac8-13b24968335f" xlink:to="loc_us-gaap_TreasuryStockValueAcquiredCostMethod_047c19a8-db04-445b-a106-1e68d628d57f" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_blkb_ExerciseOfStockOptionsAndStockAppreciationRightsShares_de754d1e-3033-433c-b192-b3e5de9ba12c" xlink:href="blkb-20240930.xsd#blkb_ExerciseOfStockOptionsAndStockAppreciationRightsShares"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_cbfb17c1-3728-4988-9ac8-13b24968335f" xlink:to="loc_blkb_ExerciseOfStockOptionsAndStockAppreciationRightsShares_de754d1e-3033-433c-b192-b3e5de9ba12c" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_blkb_ExerciseOfStockOptionsAndStockAppreciationRightsValue_6b0e21bf-7862-4160-bec0-92111d0e26ce" xlink:href="blkb-20240930.xsd#blkb_ExerciseOfStockOptionsAndStockAppreciationRightsValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_cbfb17c1-3728-4988-9ac8-13b24968335f" xlink:to="loc_blkb_ExerciseOfStockOptionsAndStockAppreciationRightsValue_6b0e21bf-7862-4160-bec0-92111d0e26ce" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharesPaidForTaxWithholdingForShareBasedCompensation_2f9b6f22-de16-46ec-ae78-7728390efa8c" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SharesPaidForTaxWithholdingForShareBasedCompensation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_cbfb17c1-3728-4988-9ac8-13b24968335f" xlink:to="loc_us-gaap_SharesPaidForTaxWithholdingForShareBasedCompensation_2f9b6f22-de16-46ec-ae78-7728390efa8c" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdjustmentsRelatedToTaxWithholdingForShareBasedCompensation_68525ffa-f8e8-42f1-aa10-05af258d0f7e" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AdjustmentsRelatedToTaxWithholdingForShareBasedCompensation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_cbfb17c1-3728-4988-9ac8-13b24968335f" xlink:to="loc_us-gaap_AdjustmentsRelatedToTaxWithholdingForShareBasedCompensation_68525ffa-f8e8-42f1-aa10-05af258d0f7e" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue_b5d2ef04-ec0a-41f0-bd2c-ef7101fa43bb" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_cbfb17c1-3728-4988-9ac8-13b24968335f" xlink:to="loc_us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue_b5d2ef04-ec0a-41f0-bd2c-ef7101fa43bb" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesRestrictedStockAwardGross_e74bce7e-d7ae-4564-b65f-c8c47ee11612" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StockIssuedDuringPeriodSharesRestrictedStockAwardGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_cbfb17c1-3728-4988-9ac8-13b24968335f" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesRestrictedStockAwardGross_e74bce7e-d7ae-4564-b65f-c8c47ee11612" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodValueRestrictedStockAwardGross_ac0d5dab-d06b-41ef-a734-8dd848a10ad9" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StockIssuedDuringPeriodValueRestrictedStockAwardGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_cbfb17c1-3728-4988-9ac8-13b24968335f" xlink:to="loc_us-gaap_StockIssuedDuringPeriodValueRestrictedStockAwardGross_ac0d5dab-d06b-41ef-a734-8dd848a10ad9" xlink:type="arc" order="15"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesRestrictedStockAwardForfeited_e03ff3c8-d125-48cd-aeac-af9c00b625fe" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StockIssuedDuringPeriodSharesRestrictedStockAwardForfeited"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_cbfb17c1-3728-4988-9ac8-13b24968335f" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesRestrictedStockAwardForfeited_e03ff3c8-d125-48cd-aeac-af9c00b625fe" xlink:type="arc" order="16"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTax_86a17d35-20d9-4abc-a608-7e105e40798b" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_OtherComprehensiveIncomeLossNetOfTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_cbfb17c1-3728-4988-9ac8-13b24968335f" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTax_86a17d35-20d9-4abc-a608-7e105e40798b" xlink:type="arc" order="17"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharesIssued_6499951f-cc7e-40f6-803e-a58537f07724" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SharesIssued"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquity_9f1abe6c-701c-49f4-bdb4-45318ba15419" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StockholdersEquity"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TreasuryStockCommonShares_8425fbd6-7a91-4d68-b872-c56962d8563d" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_TreasuryStockCommonShares"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.blackbaud.com/role/BusinessCombinationsDetails" xlink:type="simple" xlink:href="blkb-20240930.xsd#BusinessCombinationsDetails"/>
  <link:definitionLink xlink:role="http://www.blackbaud.com/role/BusinessCombinationsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementLineItems_d3fb8a1f-9f0f-4617-a964-e2c60d0c9d70" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StatementLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementTable_7e29d7bf-1be7-4e0d-b127-840b6237b4d3" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StatementTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_d3fb8a1f-9f0f-4617-a964-e2c60d0c9d70" xlink:to="loc_us-gaap_StatementTable_7e29d7bf-1be7-4e0d-b127-840b6237b4d3" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_739f91bd-675e-44d3-9ada-54887c822e2d" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_7e29d7bf-1be7-4e0d-b127-840b6237b4d3" xlink:to="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_739f91bd-675e-44d3-9ada-54887c822e2d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_739f91bd-675e-44d3-9ada-54887c822e2d_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_739f91bd-675e-44d3-9ada-54887c822e2d" xlink:to="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_739f91bd-675e-44d3-9ada-54887c822e2d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_7d9c982b-8b8e-4069-8ac5-175039099697" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_739f91bd-675e-44d3-9ada-54887c822e2d" xlink:to="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_7d9c982b-8b8e-4069-8ac5-175039099697" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_blkb_EVERFILimitedMember_fc7021c9-08e8-4e9e-9b25-fd6491422e1f" xlink:href="blkb-20240930.xsd#blkb_EVERFILimitedMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_7d9c982b-8b8e-4069-8ac5-175039099697" xlink:to="loc_blkb_EVERFILimitedMember_fc7021c9-08e8-4e9e-9b25-fd6491422e1f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_a5fafb75-2fe5-4f20-b911-90c97658ce7b" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_d3fb8a1f-9f0f-4617-a964-e2c60d0c9d70" xlink:to="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_a5fafb75-2fe5-4f20-b911-90c97658ce7b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupNotDiscontinuedOperationGainLossOnDisposal_98248ae8-d927-4d9e-bc72-ecb34f14b52c" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DisposalGroupNotDiscontinuedOperationGainLossOnDisposal"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_d3fb8a1f-9f0f-4617-a964-e2c60d0c9d70" xlink:to="loc_us-gaap_DisposalGroupNotDiscontinuedOperationGainLossOnDisposal_98248ae8-d927-4d9e-bc72-ecb34f14b52c" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.blackbaud.com/role/FairValueMeasurementsAssetsandLiabilitiesMeasuredatFairValueonaRecurringBasisDetails" xlink:type="simple" xlink:href="blkb-20240930.xsd#FairValueMeasurementsAssetsandLiabilitiesMeasuredatFairValueonaRecurringBasisDetails"/>
  <link:definitionLink xlink:role="http://www.blackbaud.com/role/FairValueMeasurementsAssetsandLiabilitiesMeasuredatFairValueonaRecurringBasisDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_4e536fe8-b7b7-49a2-9db7-e930e59f9393" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_7e963c68-5f3e-453b-a559-997bffb656d7" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_4e536fe8-b7b7-49a2-9db7-e930e59f9393" xlink:to="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_7e963c68-5f3e-453b-a559-997bffb656d7" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByMeasurementFrequencyAxis_bd3e3f5e-9b46-4e7d-a116-6e2307fc5327" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FairValueByMeasurementFrequencyAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_7e963c68-5f3e-453b-a559-997bffb656d7" xlink:to="loc_us-gaap_FairValueByMeasurementFrequencyAxis_bd3e3f5e-9b46-4e7d-a116-6e2307fc5327" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementFrequencyDomain_bd3e3f5e-9b46-4e7d-a116-6e2307fc5327_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FairValueMeasurementFrequencyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByMeasurementFrequencyAxis_bd3e3f5e-9b46-4e7d-a116-6e2307fc5327" xlink:to="loc_us-gaap_FairValueMeasurementFrequencyDomain_bd3e3f5e-9b46-4e7d-a116-6e2307fc5327_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementFrequencyDomain_5ecd12fd-18b6-463c-88fd-81c9db39d332" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FairValueMeasurementFrequencyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByMeasurementFrequencyAxis_bd3e3f5e-9b46-4e7d-a116-6e2307fc5327" xlink:to="loc_us-gaap_FairValueMeasurementFrequencyDomain_5ecd12fd-18b6-463c-88fd-81c9db39d332" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsRecurringMember_9664e325-f682-48d2-b545-e9eafdcb4224" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FairValueMeasurementsRecurringMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementFrequencyDomain_5ecd12fd-18b6-463c-88fd-81c9db39d332" xlink:to="loc_us-gaap_FairValueMeasurementsRecurringMember_9664e325-f682-48d2-b545-e9eafdcb4224" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_d34053c1-e43a-4ce3-a310-3ae269ab3145" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_7e963c68-5f3e-453b-a559-997bffb656d7" xlink:to="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_d34053c1-e43a-4ce3-a310-3ae269ab3145" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_d34053c1-e43a-4ce3-a310-3ae269ab3145_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_d34053c1-e43a-4ce3-a310-3ae269ab3145" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_d34053c1-e43a-4ce3-a310-3ae269ab3145_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_04da6394-d978-41ca-bd3a-1b9c79025ec2" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_d34053c1-e43a-4ce3-a310-3ae269ab3145" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_04da6394-d978-41ca-bd3a-1b9c79025ec2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel1Member_9a602745-bc49-460e-8269-b4cfdc142e84" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FairValueInputsLevel1Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_04da6394-d978-41ca-bd3a-1b9c79025ec2" xlink:to="loc_us-gaap_FairValueInputsLevel1Member_9a602745-bc49-460e-8269-b4cfdc142e84" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel2Member_ff765837-3dc8-4bd8-b258-0900918bdacd" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FairValueInputsLevel2Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_04da6394-d978-41ca-bd3a-1b9c79025ec2" xlink:to="loc_us-gaap_FairValueInputsLevel2Member_ff765837-3dc8-4bd8-b258-0900918bdacd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel3Member_19220728-515d-4189-af88-cfd56e261fd0" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FairValueInputsLevel3Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_04da6394-d978-41ca-bd3a-1b9c79025ec2" xlink:to="loc_us-gaap_FairValueInputsLevel3Member_19220728-515d-4189-af88-cfd56e261fd0" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeAssets_fc936799-bb30-44ce-b535-51454ebfbf61" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DerivativeAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_4e536fe8-b7b7-49a2-9db7-e930e59f9393" xlink:to="loc_us-gaap_DerivativeAssets_fc936799-bb30-44ce-b535-51454ebfbf61" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ForeignCurrencyContractAssetFairValueDisclosure_08b7f74e-8481-4b69-9a64-a0089d148deb" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ForeignCurrencyContractAssetFairValueDisclosure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_4e536fe8-b7b7-49a2-9db7-e930e59f9393" xlink:to="loc_us-gaap_ForeignCurrencyContractAssetFairValueDisclosure_08b7f74e-8481-4b69-9a64-a0089d148deb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsFairValueDisclosure_463b0ec7-4a62-4f11-b800-e2dd02755694" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AssetsFairValueDisclosure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_4e536fe8-b7b7-49a2-9db7-e930e59f9393" xlink:to="loc_us-gaap_AssetsFairValueDisclosure_463b0ec7-4a62-4f11-b800-e2dd02755694" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeLiabilities_d4097614-751a-462e-8611-d6de1c8f5430" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DerivativeLiabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_4e536fe8-b7b7-49a2-9db7-e930e59f9393" xlink:to="loc_us-gaap_DerivativeLiabilities_d4097614-751a-462e-8611-d6de1c8f5430" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ForeignCurrencyContractsLiabilityFairValueDisclosure_716a50f0-f110-4a5d-b5a6-5dbc9b007f2a" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ForeignCurrencyContractsLiabilityFairValueDisclosure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_4e536fe8-b7b7-49a2-9db7-e930e59f9393" xlink:to="loc_us-gaap_ForeignCurrencyContractsLiabilityFairValueDisclosure_716a50f0-f110-4a5d-b5a6-5dbc9b007f2a" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationContingentConsiderationLiability_952b7bc5-1a9b-44e8-90b3-a36742368d15" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_BusinessCombinationContingentConsiderationLiability"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_4e536fe8-b7b7-49a2-9db7-e930e59f9393" xlink:to="loc_us-gaap_BusinessCombinationContingentConsiderationLiability_952b7bc5-1a9b-44e8-90b3-a36742368d15" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesFairValueDisclosure_8143427c-125d-4851-bff0-8e2d3cb39548" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LiabilitiesFairValueDisclosure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_4e536fe8-b7b7-49a2-9db7-e930e59f9393" xlink:to="loc_us-gaap_LiabilitiesFairValueDisclosure_8143427c-125d-4851-bff0-8e2d3cb39548" xlink:type="arc" order="6"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.blackbaud.com/role/DebtDetails" xlink:type="simple" xlink:href="blkb-20240930.xsd#DebtDetails"/>
  <link:definitionLink xlink:role="http://www.blackbaud.com/role/DebtDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionLineItems_d75208fc-3ed9-4b50-b25d-69b940dadc12" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_BusinessAcquisitionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentTable_d9f31be9-2304-4d70-81cc-6003e83651d5" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DebtInstrumentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_d75208fc-3ed9-4b50-b25d-69b940dadc12" xlink:to="loc_us-gaap_DebtInstrumentTable_d9f31be9-2304-4d70-81cc-6003e83651d5" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis_6c13c3a9-2e48-49cf-8469-dde8f83611ba" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_d9f31be9-2304-4d70-81cc-6003e83651d5" xlink:to="loc_srt_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis_6c13c3a9-2e48-49cf-8469-dde8f83611ba" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RealEstateAndAccumulatedDepreciationNameOfPropertyDomain_6c13c3a9-2e48-49cf-8469-dde8f83611ba_default" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_RealEstateAndAccumulatedDepreciationNameOfPropertyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis_6c13c3a9-2e48-49cf-8469-dde8f83611ba" xlink:to="loc_srt_RealEstateAndAccumulatedDepreciationNameOfPropertyDomain_6c13c3a9-2e48-49cf-8469-dde8f83611ba_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RealEstateAndAccumulatedDepreciationNameOfPropertyDomain_a053c57b-c577-44c6-847c-49826971b81b" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_RealEstateAndAccumulatedDepreciationNameOfPropertyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis_6c13c3a9-2e48-49cf-8469-dde8f83611ba" xlink:to="loc_srt_RealEstateAndAccumulatedDepreciationNameOfPropertyDomain_a053c57b-c577-44c6-847c-49826971b81b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_blkb_GlobalHQMember_abc5641c-f8f8-4801-bab3-8363d847257e" xlink:href="blkb-20240930.xsd#blkb_GlobalHQMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RealEstateAndAccumulatedDepreciationNameOfPropertyDomain_a053c57b-c577-44c6-847c-49826971b81b" xlink:to="loc_blkb_GlobalHQMember_abc5641c-f8f8-4801-bab3-8363d847257e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityAxis_0b2911b0-87d1-41da-918a-7eae586e718f" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CreditFacilityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_d9f31be9-2304-4d70-81cc-6003e83651d5" xlink:to="loc_us-gaap_CreditFacilityAxis_0b2911b0-87d1-41da-918a-7eae586e718f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_0b2911b0-87d1-41da-918a-7eae586e718f_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_CreditFacilityAxis_0b2911b0-87d1-41da-918a-7eae586e718f" xlink:to="loc_us-gaap_CreditFacilityDomain_0b2911b0-87d1-41da-918a-7eae586e718f_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_173e9b0a-0b37-4da0-b49a-48e8aa9a3a9b" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_CreditFacilityAxis_0b2911b0-87d1-41da-918a-7eae586e718f" xlink:to="loc_us-gaap_CreditFacilityDomain_173e9b0a-0b37-4da0-b49a-48e8aa9a3a9b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevolvingCreditFacilityMember_93768f21-d7b6-48a0-ae0d-2d22d46ad85f" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RevolvingCreditFacilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_173e9b0a-0b37-4da0-b49a-48e8aa9a3a9b" xlink:to="loc_us-gaap_RevolvingCreditFacilityMember_93768f21-d7b6-48a0-ae0d-2d22d46ad85f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SecuredDebtMember_92bb0941-75d6-4fce-8a22-5c977281a023" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SecuredDebtMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_173e9b0a-0b37-4da0-b49a-48e8aa9a3a9b" xlink:to="loc_us-gaap_SecuredDebtMember_92bb0941-75d6-4fce-8a22-5c977281a023" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StandbyLettersOfCreditMember_4ab7ce42-c621-4a12-a87d-74ee061c0029" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StandbyLettersOfCreditMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_173e9b0a-0b37-4da0-b49a-48e8aa9a3a9b" xlink:to="loc_us-gaap_StandbyLettersOfCreditMember_4ab7ce42-c621-4a12-a87d-74ee061c0029" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_blkb_SwinglineloansMember_d949a4c2-2bce-4417-b683-4e431291d80d" xlink:href="blkb-20240930.xsd#blkb_SwinglineloansMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_173e9b0a-0b37-4da0-b49a-48e8aa9a3a9b" xlink:to="loc_blkb_SwinglineloansMember_d949a4c2-2bce-4417-b683-4e431291d80d" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ForeignLineOfCreditMember_cde1d009-2b86-4273-bbd3-c2d33d7ba431" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ForeignLineOfCreditMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_173e9b0a-0b37-4da0-b49a-48e8aa9a3a9b" xlink:to="loc_us-gaap_ForeignLineOfCreditMember_cde1d009-2b86-4273-bbd3-c2d33d7ba431" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VariableRateAxis_1a210595-020e-472b-ac65-e4f33a8a2d61" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_VariableRateAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_d9f31be9-2304-4d70-81cc-6003e83651d5" xlink:to="loc_us-gaap_VariableRateAxis_1a210595-020e-472b-ac65-e4f33a8a2d61" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VariableRateDomain_1a210595-020e-472b-ac65-e4f33a8a2d61_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_VariableRateDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_VariableRateAxis_1a210595-020e-472b-ac65-e4f33a8a2d61" xlink:to="loc_us-gaap_VariableRateDomain_1a210595-020e-472b-ac65-e4f33a8a2d61_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VariableRateDomain_d111ac61-6514-4372-a3b7-d5fe79e0f93e" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_VariableRateDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_VariableRateAxis_1a210595-020e-472b-ac65-e4f33a8a2d61" xlink:to="loc_us-gaap_VariableRateDomain_d111ac61-6514-4372-a3b7-d5fe79e0f93e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FederalFundsEffectiveSwapRateMember_d4c4552a-37cb-4eea-a6bc-f9b749050ab1" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FederalFundsEffectiveSwapRateMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VariableRateDomain_d111ac61-6514-4372-a3b7-d5fe79e0f93e" xlink:to="loc_us-gaap_FederalFundsEffectiveSwapRateMember_d4c4552a-37cb-4eea-a6bc-f9b749050ab1" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SecuredOvernightFinancingRateSofrOvernightIndexSwapRateMember_d05a4d63-f28b-4348-b671-a1b712c8fe30" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SecuredOvernightFinancingRateSofrOvernightIndexSwapRateMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VariableRateDomain_d111ac61-6514-4372-a3b7-d5fe79e0f93e" xlink:to="loc_us-gaap_SecuredOvernightFinancingRateSofrOvernightIndexSwapRateMember_d05a4d63-f28b-4348-b671-a1b712c8fe30" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BaseRateMember_49846d89-cf18-45b1-86b1-ba37dd1c77a9" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_BaseRateMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VariableRateDomain_d111ac61-6514-4372-a3b7-d5fe79e0f93e" xlink:to="loc_us-gaap_BaseRateMember_49846d89-cf18-45b1-86b1-ba37dd1c77a9" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_blkb_DesignatedCurrencyRateMember_1da166e0-45d9-496c-a140-17aa30fabfd5" xlink:href="blkb-20240930.xsd#blkb_DesignatedCurrencyRateMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VariableRateDomain_d111ac61-6514-4372-a3b7-d5fe79e0f93e" xlink:to="loc_blkb_DesignatedCurrencyRateMember_1da166e0-45d9-496c-a140-17aa30fabfd5" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_b6b11c7f-de8b-4e90-8f72-de51c5e60e6f" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_d9f31be9-2304-4d70-81cc-6003e83651d5" xlink:to="loc_srt_RangeAxis_b6b11c7f-de8b-4e90-8f72-de51c5e60e6f" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_b6b11c7f-de8b-4e90-8f72-de51c5e60e6f_default" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_b6b11c7f-de8b-4e90-8f72-de51c5e60e6f" xlink:to="loc_srt_RangeMember_b6b11c7f-de8b-4e90-8f72-de51c5e60e6f_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_429f2a9b-ec72-47ca-b4eb-1c6071a7a544" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_b6b11c7f-de8b-4e90-8f72-de51c5e60e6f" xlink:to="loc_srt_RangeMember_429f2a9b-ec72-47ca-b4eb-1c6071a7a544" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_cc196b2f-21cc-4575-900a-13163e90b3ee" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_429f2a9b-ec72-47ca-b4eb-1c6071a7a544" xlink:to="loc_srt_MinimumMember_cc196b2f-21cc-4575-900a-13163e90b3ee" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_3b7325e7-7d6f-445f-904e-617f8903a332" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_429f2a9b-ec72-47ca-b4eb-1c6071a7a544" xlink:to="loc_srt_MaximumMember_3b7325e7-7d6f-445f-904e-617f8903a332" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_17623562-0dc7-42ea-806c-dda88d583594" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_d75208fc-3ed9-4b50-b25d-69b940dadc12" xlink:to="loc_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_17623562-0dc7-42ea-806c-dda88d583594" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromLinesOfCredit_c484bf4d-4af4-4351-b6f6-30ddf5cea789" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ProceedsFromLinesOfCredit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_d75208fc-3ed9-4b50-b25d-69b940dadc12" xlink:to="loc_us-gaap_ProceedsFromLinesOfCredit_c484bf4d-4af4-4351-b6f6-30ddf5cea789" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RepaymentsOfLinesOfCredit_be6c6b70-6a39-4ef5-9d2d-87cc2a4be492" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RepaymentsOfLinesOfCredit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_d75208fc-3ed9-4b50-b25d-69b940dadc12" xlink:to="loc_us-gaap_RepaymentsOfLinesOfCredit_be6c6b70-6a39-4ef5-9d2d-87cc2a4be492" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsOfFinancingCosts_f1969f82-4884-4f58-abfd-71c71b78ac02" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PaymentsOfFinancingCosts"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_d75208fc-3ed9-4b50-b25d-69b940dadc12" xlink:to="loc_us-gaap_PaymentsOfFinancingCosts_f1969f82-4884-4f58-abfd-71c71b78ac02" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsOfDebtIssuanceCosts_4369efed-6834-47bf-b32b-6f96c2cbc6b2" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PaymentsOfDebtIssuanceCosts"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_d75208fc-3ed9-4b50-b25d-69b940dadc12" xlink:to="loc_us-gaap_PaymentsOfDebtIssuanceCosts_4369efed-6834-47bf-b32b-6f96c2cbc6b2" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtIssuanceCostsLineOfCreditArrangementsNet_e66185b2-f47c-42f1-b3eb-a157bd040146" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DebtIssuanceCostsLineOfCreditArrangementsNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_d75208fc-3ed9-4b50-b25d-69b940dadc12" xlink:to="loc_us-gaap_DebtIssuanceCostsLineOfCreditArrangementsNet_e66185b2-f47c-42f1-b3eb-a157bd040146" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentUnamortizedDiscountPremiumAndDebtIssuanceCostsNet_1eab641a-3854-46e1-911d-eeeed344274c" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DebtInstrumentUnamortizedDiscountPremiumAndDebtIssuanceCostsNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_d75208fc-3ed9-4b50-b25d-69b940dadc12" xlink:to="loc_us-gaap_DebtInstrumentUnamortizedDiscountPremiumAndDebtIssuanceCostsNet_1eab641a-3854-46e1-911d-eeeed344274c" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_blkb_LineOfCreditFacilityVariableInterestRate_1fce8156-98ff-4f0e-9be2-0ed958f6cb1f" xlink:href="blkb-20240930.xsd#blkb_LineOfCreditFacilityVariableInterestRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_d75208fc-3ed9-4b50-b25d-69b940dadc12" xlink:to="loc_blkb_LineOfCreditFacilityVariableInterestRate_1fce8156-98ff-4f0e-9be2-0ed958f6cb1f" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentBasisSpreadOnVariableRate1_d1891093-5a51-4d99-b95d-bd9b505116cb" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DebtInstrumentBasisSpreadOnVariableRate1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_d75208fc-3ed9-4b50-b25d-69b940dadc12" xlink:to="loc_us-gaap_DebtInstrumentBasisSpreadOnVariableRate1_d1891093-5a51-4d99-b95d-bd9b505116cb" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityUnusedCapacityCommitmentFeePercentage_445c1c6a-6385-420a-8335-16d7069cf64a" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LineOfCreditFacilityUnusedCapacityCommitmentFeePercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_d75208fc-3ed9-4b50-b25d-69b940dadc12" xlink:to="loc_us-gaap_LineOfCreditFacilityUnusedCapacityCommitmentFeePercentage_445c1c6a-6385-420a-8335-16d7069cf64a" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_blkb_LineofCreditFacilityAvailableIncreaseCapacityAmount_8e8b3157-c4cc-4f87-854c-8772a11e9231" xlink:href="blkb-20240930.xsd#blkb_LineofCreditFacilityAvailableIncreaseCapacityAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_d75208fc-3ed9-4b50-b25d-69b940dadc12" xlink:to="loc_blkb_LineofCreditFacilityAvailableIncreaseCapacityAmount_8e8b3157-c4cc-4f87-854c-8772a11e9231" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_blkb_LineOfCreditFacilityAvailableIncreaseCapacityPercentOfEBITDA_874affd5-e0a7-4d05-8f73-070fd94ef37d" xlink:href="blkb-20240930.xsd#blkb_LineOfCreditFacilityAvailableIncreaseCapacityPercentOfEBITDA"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_d75208fc-3ed9-4b50-b25d-69b940dadc12" xlink:to="loc_blkb_LineOfCreditFacilityAvailableIncreaseCapacityPercentOfEBITDA_874affd5-e0a7-4d05-8f73-070fd94ef37d" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_blkb_NetLeverageRatio_79fadca2-158e-4222-a4c4-6f4978b217d9" xlink:href="blkb-20240930.xsd#blkb_NetLeverageRatio"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_d75208fc-3ed9-4b50-b25d-69b940dadc12" xlink:to="loc_blkb_NetLeverageRatio_79fadca2-158e-4222-a4c4-6f4978b217d9" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentFaceAmount_3998f38f-9bdb-480e-b35b-1794bcd4f8ce" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DebtInstrumentFaceAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_d75208fc-3ed9-4b50-b25d-69b940dadc12" xlink:to="loc_us-gaap_DebtInstrumentFaceAmount_3998f38f-9bdb-480e-b35b-1794bcd4f8ce" xlink:type="arc" order="13"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.blackbaud.com/role/DebtSummaryofDebtDetails" xlink:type="simple" xlink:href="blkb-20240930.xsd#DebtSummaryofDebtDetails"/>
  <link:definitionLink xlink:role="http://www.blackbaud.com/role/DebtSummaryofDebtDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityLineItems_c665cbcb-b975-4f52-9cd5-9656f4634ebb" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LineOfCreditFacilityLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityTable_8efa7fa9-d0ad-4ca7-a5f1-5c5c8ea93e5d" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LineOfCreditFacilityTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_c665cbcb-b975-4f52-9cd5-9656f4634ebb" xlink:to="loc_us-gaap_LineOfCreditFacilityTable_8efa7fa9-d0ad-4ca7-a5f1-5c5c8ea93e5d" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityAxis_e0fa0a1c-1be4-4d8e-bfd1-fb24506f4bb4" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CreditFacilityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LineOfCreditFacilityTable_8efa7fa9-d0ad-4ca7-a5f1-5c5c8ea93e5d" xlink:to="loc_us-gaap_CreditFacilityAxis_e0fa0a1c-1be4-4d8e-bfd1-fb24506f4bb4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_e0fa0a1c-1be4-4d8e-bfd1-fb24506f4bb4_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_CreditFacilityAxis_e0fa0a1c-1be4-4d8e-bfd1-fb24506f4bb4" xlink:to="loc_us-gaap_CreditFacilityDomain_e0fa0a1c-1be4-4d8e-bfd1-fb24506f4bb4_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_b4feb8d9-c235-45ea-85c0-3c6401b91123" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_CreditFacilityAxis_e0fa0a1c-1be4-4d8e-bfd1-fb24506f4bb4" xlink:to="loc_us-gaap_CreditFacilityDomain_b4feb8d9-c235-45ea-85c0-3c6401b91123" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevolvingCreditFacilityMember_149e7dc9-928d-45d6-ab68-afe4ea21a959" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RevolvingCreditFacilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_b4feb8d9-c235-45ea-85c0-3c6401b91123" xlink:to="loc_us-gaap_RevolvingCreditFacilityMember_149e7dc9-928d-45d6-ab68-afe4ea21a959" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SecuredDebtMember_43c7dcd0-3f68-4808-909b-636645a0f49e" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SecuredDebtMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_b4feb8d9-c235-45ea-85c0-3c6401b91123" xlink:to="loc_us-gaap_SecuredDebtMember_43c7dcd0-3f68-4808-909b-636645a0f49e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MortgagesMember_b6005eb8-88cc-4156-8fad-db4af53e667d" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_MortgagesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_b4feb8d9-c235-45ea-85c0-3c6401b91123" xlink:to="loc_us-gaap_MortgagesMember_b6005eb8-88cc-4156-8fad-db4af53e667d" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LoansPayableMember_979aa25e-c7ad-494b-954e-6314e9fa1ffe" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LoansPayableMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_b4feb8d9-c235-45ea-85c0-3c6401b91123" xlink:to="loc_us-gaap_LoansPayableMember_979aa25e-c7ad-494b-954e-6314e9fa1ffe" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShortTermDebtMember_3651cba9-f736-4b65-80fd-c280684cd883" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShortTermDebtMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_b4feb8d9-c235-45ea-85c0-3c6401b91123" xlink:to="loc_us-gaap_ShortTermDebtMember_3651cba9-f736-4b65-80fd-c280684cd883" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebtMember_e85dac60-aeef-4730-9a2e-0e47d2191528" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LongTermDebtMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_b4feb8d9-c235-45ea-85c0-3c6401b91123" xlink:to="loc_us-gaap_LongTermDebtMember_e85dac60-aeef-4730-9a2e-0e47d2191528" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentCarryingAmount_ea54748e-8599-4b99-8f92-1ba89ed715dc" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DebtInstrumentCarryingAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_c665cbcb-b975-4f52-9cd5-9656f4634ebb" xlink:to="loc_us-gaap_DebtInstrumentCarryingAmount_ea54748e-8599-4b99-8f92-1ba89ed715dc" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SupplierFinanceProgramObligation_7712efb6-a4ce-4a04-9795-9c0439fe5947" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SupplierFinanceProgramObligation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_c665cbcb-b975-4f52-9cd5-9656f4634ebb" xlink:to="loc_us-gaap_SupplierFinanceProgramObligation_7712efb6-a4ce-4a04-9795-9c0439fe5947" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentUnamortizedDiscountPremiumAndDebtIssuanceCostsNet_8aed48a2-bb6c-41e9-bd0b-6b81b0de37d4" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DebtInstrumentUnamortizedDiscountPremiumAndDebtIssuanceCostsNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_c665cbcb-b975-4f52-9cd5-9656f4634ebb" xlink:to="loc_us-gaap_DebtInstrumentUnamortizedDiscountPremiumAndDebtIssuanceCostsNet_8aed48a2-bb6c-41e9-bd0b-6b81b0de37d4" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebtCurrent_f600cab2-c627-49cd-ab31-948f446e793a" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LongTermDebtCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_c665cbcb-b975-4f52-9cd5-9656f4634ebb" xlink:to="loc_us-gaap_LongTermDebtCurrent_f600cab2-c627-49cd-ab31-948f446e793a" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebtNoncurrent_99483513-913c-479b-b7e8-d8b6ee3af74a" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LongTermDebtNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_c665cbcb-b975-4f52-9cd5-9656f4634ebb" xlink:to="loc_us-gaap_LongTermDebtNoncurrent_99483513-913c-479b-b7e8-d8b6ee3af74a" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentInterestRateEffectivePercentage_c27e8484-438d-4231-82ee-bd44123a63d1" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DebtInstrumentInterestRateEffectivePercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_c665cbcb-b975-4f52-9cd5-9656f4634ebb" xlink:to="loc_us-gaap_DebtInstrumentInterestRateEffectivePercentage_c27e8484-438d-4231-82ee-bd44123a63d1" xlink:type="arc" order="5"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.blackbaud.com/role/DebtSummaryofCurrentlyEffectiveThirdPartyFinancingAgreementsDetails" xlink:type="simple" xlink:href="blkb-20240930.xsd#DebtSummaryofCurrentlyEffectiveThirdPartyFinancingAgreementsDetails"/>
  <link:definitionLink xlink:role="http://www.blackbaud.com/role/DebtSummaryofCurrentlyEffectiveThirdPartyFinancingAgreementsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentLineItems_d5f16298-6c78-4fca-9a51-16285ba145a1" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DebtInstrumentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentTable_a90fd6bd-8cd9-4714-9e7a-ab43371fff7d" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DebtInstrumentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DebtInstrumentLineItems_d5f16298-6c78-4fca-9a51-16285ba145a1" xlink:to="loc_us-gaap_DebtInstrumentTable_a90fd6bd-8cd9-4714-9e7a-ab43371fff7d" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_4d46f7ca-dabb-4991-a0dd-0d641a37df16" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LongtermDebtTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_a90fd6bd-8cd9-4714-9e7a-ab43371fff7d" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_4d46f7ca-dabb-4991-a0dd-0d641a37df16" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_4d46f7ca-dabb-4991-a0dd-0d641a37df16_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_4d46f7ca-dabb-4991-a0dd-0d641a37df16" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_4d46f7ca-dabb-4991-a0dd-0d641a37df16_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_ac6ca6a7-effa-4397-91d3-6570f1c75636" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_4d46f7ca-dabb-4991-a0dd-0d641a37df16" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_ac6ca6a7-effa-4397-91d3-6570f1c75636" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LoansPayableMember_c9d924d1-d669-4628-b657-0ee8e8c76c5c" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LoansPayableMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_ac6ca6a7-effa-4397-91d3-6570f1c75636" xlink:to="loc_us-gaap_LoansPayableMember_c9d924d1-d669-4628-b657-0ee8e8c76c5c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentFaceAmount_9d6a02dd-9676-4cdd-94b9-3fff44e820ef" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DebtInstrumentFaceAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_d5f16298-6c78-4fca-9a51-16285ba145a1" xlink:to="loc_us-gaap_DebtInstrumentFaceAmount_9d6a02dd-9676-4cdd-94b9-3fff44e820ef" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.blackbaud.com/role/DerivativeInstrumentsDetails" xlink:type="simple" xlink:href="blkb-20240930.xsd#DerivativeInstrumentsDetails"/>
  <link:definitionLink xlink:role="http://www.blackbaud.com/role/DerivativeInstrumentsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeLineItems_d189277e-5c99-4c3f-8115-eae7904f3289" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DerivativeLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeTable_9834ec6b-7bb7-45b8-9402-d78b338b018d" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DerivativeTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DerivativeLineItems_d189277e-5c99-4c3f-8115-eae7904f3289" xlink:to="loc_us-gaap_DerivativeTable_9834ec6b-7bb7-45b8-9402-d78b338b018d" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_2988b5c0-8ece-44d1-bce4-d8b324a4b665" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DerivativeInstrumentRiskAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_9834ec6b-7bb7-45b8-9402-d78b338b018d" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_2988b5c0-8ece-44d1-bce4-d8b324a4b665" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_2988b5c0-8ece-44d1-bce4-d8b324a4b665_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_2988b5c0-8ece-44d1-bce4-d8b324a4b665" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_2988b5c0-8ece-44d1-bce4-d8b324a4b665_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_7c6251c8-c7cc-4e00-bf80-8f1ec4a05d83" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_2988b5c0-8ece-44d1-bce4-d8b324a4b665" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_7c6251c8-c7cc-4e00-bf80-8f1ec4a05d83" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_blkb_September2024Swap1Member_37d46632-86c2-415f-9964-54bc2cbd54f2" xlink:href="blkb-20240930.xsd#blkb_September2024Swap1Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_7c6251c8-c7cc-4e00-bf80-8f1ec4a05d83" xlink:to="loc_blkb_September2024Swap1Member_37d46632-86c2-415f-9964-54bc2cbd54f2" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_blkb_September2024Swap2Member_4d56ea55-8f68-476b-8006-e1981ea5da46" xlink:href="blkb-20240930.xsd#blkb_September2024Swap2Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_7c6251c8-c7cc-4e00-bf80-8f1ec4a05d83" xlink:to="loc_blkb_September2024Swap2Member_4d56ea55-8f68-476b-8006-e1981ea5da46" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestRateSwapMember_464bc111-469d-49e5-bd94-1013d1029907" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_InterestRateSwapMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_7c6251c8-c7cc-4e00-bf80-8f1ec4a05d83" xlink:to="loc_us-gaap_InterestRateSwapMember_464bc111-469d-49e5-bd94-1013d1029907" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ForeignExchangeForwardMember_d8f27064-0371-4358-9c6b-d5689b949f2d" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ForeignExchangeForwardMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_7c6251c8-c7cc-4e00-bf80-8f1ec4a05d83" xlink:to="loc_us-gaap_ForeignExchangeForwardMember_d8f27064-0371-4358-9c6b-d5689b949f2d" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeNotionalAmount_79de6495-75a2-4f21-8f8d-8a7edaade1d5" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DerivativeNotionalAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_d189277e-5c99-4c3f-8115-eae7904f3289" xlink:to="loc_us-gaap_DerivativeNotionalAmount_79de6495-75a2-4f21-8f8d-8a7edaade1d5" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashFlowHedgeGainLossToBeReclassifiedWithinTwelveMonths_083b5d88-ac58-477d-b830-c23069e044e4" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CashFlowHedgeGainLossToBeReclassifiedWithinTwelveMonths"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_d189277e-5c99-4c3f-8115-eae7904f3289" xlink:to="loc_us-gaap_CashFlowHedgeGainLossToBeReclassifiedWithinTwelveMonths_083b5d88-ac58-477d-b830-c23069e044e4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GainLossOnCashFlowHedgeIneffectivenessNet_b51fd410-d1f8-41f2-a5b9-36f44e6e9000" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_GainLossOnCashFlowHedgeIneffectivenessNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_d189277e-5c99-4c3f-8115-eae7904f3289" xlink:to="loc_us-gaap_GainLossOnCashFlowHedgeIneffectivenessNet_b51fd410-d1f8-41f2-a5b9-36f44e6e9000" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeLiabilityCurrentStatementOfFinancialPositionExtensibleEnumeration_d7306864-6883-4874-8932-c8d16a050c47" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DerivativeLiabilityCurrentStatementOfFinancialPositionExtensibleEnumeration"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_d189277e-5c99-4c3f-8115-eae7904f3289" xlink:to="loc_us-gaap_DerivativeLiabilityCurrentStatementOfFinancialPositionExtensibleEnumeration_d7306864-6883-4874-8932-c8d16a050c47" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.blackbaud.com/role/DerivativeInstrumentsFairValueofDerivativeInstrumentsDetails" xlink:type="simple" xlink:href="blkb-20240930.xsd#DerivativeInstrumentsFairValueofDerivativeInstrumentsDetails"/>
  <link:definitionLink xlink:role="http://www.blackbaud.com/role/DerivativeInstrumentsFairValueofDerivativeInstrumentsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativesFairValueLineItems_75f6725e-25ba-4abb-816f-74d32ed34636" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DerivativesFairValueLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValuesDerivativesBalanceSheetLocationByDerivativeContractTypeByHedgingDesignationTable_31979a92-0375-4041-b578-3b40fca8a2fb" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FairValuesDerivativesBalanceSheetLocationByDerivativeContractTypeByHedgingDesignationTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DerivativesFairValueLineItems_75f6725e-25ba-4abb-816f-74d32ed34636" xlink:to="loc_us-gaap_FairValuesDerivativesBalanceSheetLocationByDerivativeContractTypeByHedgingDesignationTable_31979a92-0375-4041-b578-3b40fca8a2fb" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationAxis_10d00cac-42a0-4398-bf60-0e09c67ca0d7" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_HedgingDesignationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValuesDerivativesBalanceSheetLocationByDerivativeContractTypeByHedgingDesignationTable_31979a92-0375-4041-b578-3b40fca8a2fb" xlink:to="loc_us-gaap_HedgingDesignationAxis_10d00cac-42a0-4398-bf60-0e09c67ca0d7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationDomain_10d00cac-42a0-4398-bf60-0e09c67ca0d7_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_HedgingDesignationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_HedgingDesignationAxis_10d00cac-42a0-4398-bf60-0e09c67ca0d7" xlink:to="loc_us-gaap_HedgingDesignationDomain_10d00cac-42a0-4398-bf60-0e09c67ca0d7_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationDomain_9ab73e49-f475-49e7-8115-7b1679902046" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_HedgingDesignationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_HedgingDesignationAxis_10d00cac-42a0-4398-bf60-0e09c67ca0d7" xlink:to="loc_us-gaap_HedgingDesignationDomain_9ab73e49-f475-49e7-8115-7b1679902046" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DesignatedAsHedgingInstrumentMember_af9293cc-f6e1-4a47-92d9-bdbff47ac139" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DesignatedAsHedgingInstrumentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HedgingDesignationDomain_9ab73e49-f475-49e7-8115-7b1679902046" xlink:to="loc_us-gaap_DesignatedAsHedgingInstrumentMember_af9293cc-f6e1-4a47-92d9-bdbff47ac139" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_2e066b58-918c-41d1-86c6-7b9a0566ea3a" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DerivativeInstrumentRiskAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValuesDerivativesBalanceSheetLocationByDerivativeContractTypeByHedgingDesignationTable_31979a92-0375-4041-b578-3b40fca8a2fb" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_2e066b58-918c-41d1-86c6-7b9a0566ea3a" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_2e066b58-918c-41d1-86c6-7b9a0566ea3a_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_2e066b58-918c-41d1-86c6-7b9a0566ea3a" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_2e066b58-918c-41d1-86c6-7b9a0566ea3a_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_3cd45909-e876-4c41-b3bb-a460c4cf5e1f" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_2e066b58-918c-41d1-86c6-7b9a0566ea3a" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_3cd45909-e876-4c41-b3bb-a460c4cf5e1f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ForeignExchangeForwardMember_157645fb-51b4-44ff-bb8f-7b353d7c3937" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ForeignExchangeForwardMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_3cd45909-e876-4c41-b3bb-a460c4cf5e1f" xlink:to="loc_us-gaap_ForeignExchangeForwardMember_157645fb-51b4-44ff-bb8f-7b353d7c3937" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestRateSwapMember_ec4779a7-0798-4dba-be41-2896510a73cb" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_InterestRateSwapMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_3cd45909-e876-4c41-b3bb-a460c4cf5e1f" xlink:to="loc_us-gaap_InterestRateSwapMember_ec4779a7-0798-4dba-be41-2896510a73cb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeAssetsCurrent_f8513d43-9298-46dd-bdca-eef951e122b7" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DerivativeAssetsCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativesFairValueLineItems_75f6725e-25ba-4abb-816f-74d32ed34636" xlink:to="loc_us-gaap_DerivativeAssetsCurrent_f8513d43-9298-46dd-bdca-eef951e122b7" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeLiabilitiesCurrent_31711047-5b89-4d95-8d54-a879da639e75" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DerivativeLiabilitiesCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativesFairValueLineItems_75f6725e-25ba-4abb-816f-74d32ed34636" xlink:to="loc_us-gaap_DerivativeLiabilitiesCurrent_31711047-5b89-4d95-8d54-a879da639e75" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeAssetsNoncurrent_439e7519-7887-46d7-bd7f-cc5e83d17ad4" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DerivativeAssetsNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativesFairValueLineItems_75f6725e-25ba-4abb-816f-74d32ed34636" xlink:to="loc_us-gaap_DerivativeAssetsNoncurrent_439e7519-7887-46d7-bd7f-cc5e83d17ad4" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeLiabilitiesNoncurrent_b8097dcc-380e-4538-91ea-b4c96828e627" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DerivativeLiabilitiesNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativesFairValueLineItems_75f6725e-25ba-4abb-816f-74d32ed34636" xlink:to="loc_us-gaap_DerivativeLiabilitiesNoncurrent_b8097dcc-380e-4538-91ea-b4c96828e627" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeFairValueOfDerivativeAssetAmountNotOffsetAgainstCollateral_2ec1e2c2-e479-4694-81ce-6e5c329e6f75" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DerivativeFairValueOfDerivativeAssetAmountNotOffsetAgainstCollateral"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativesFairValueLineItems_75f6725e-25ba-4abb-816f-74d32ed34636" xlink:to="loc_us-gaap_DerivativeFairValueOfDerivativeAssetAmountNotOffsetAgainstCollateral_2ec1e2c2-e479-4694-81ce-6e5c329e6f75" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeFairValueOfDerivativeLiabilityAmountNotOffsetAgainstCollateral_11f19fa0-323e-42ed-b3e6-debee51aefcb" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DerivativeFairValueOfDerivativeLiabilityAmountNotOffsetAgainstCollateral"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativesFairValueLineItems_75f6725e-25ba-4abb-816f-74d32ed34636" xlink:to="loc_us-gaap_DerivativeFairValueOfDerivativeLiabilityAmountNotOffsetAgainstCollateral_11f19fa0-323e-42ed-b3e6-debee51aefcb" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeAssetCurrentStatementOfFinancialPositionExtensibleEnumeration_f9ef6807-011d-4441-a75c-a5fcd03def5b" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DerivativeAssetCurrentStatementOfFinancialPositionExtensibleEnumeration"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativesFairValueLineItems_75f6725e-25ba-4abb-816f-74d32ed34636" xlink:to="loc_us-gaap_DerivativeAssetCurrentStatementOfFinancialPositionExtensibleEnumeration_f9ef6807-011d-4441-a75c-a5fcd03def5b" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeAssetNoncurrentStatementOfFinancialPositionExtensibleEnumeration_73ed6f51-7543-4ecb-8ed9-3d05f123e7b4" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DerivativeAssetNoncurrentStatementOfFinancialPositionExtensibleEnumeration"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativesFairValueLineItems_75f6725e-25ba-4abb-816f-74d32ed34636" xlink:to="loc_us-gaap_DerivativeAssetNoncurrentStatementOfFinancialPositionExtensibleEnumeration_73ed6f51-7543-4ecb-8ed9-3d05f123e7b4" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeLiabilityCurrentStatementOfFinancialPositionExtensibleEnumeration_c6d208fe-f869-43ac-a58d-d284070dbd61" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DerivativeLiabilityCurrentStatementOfFinancialPositionExtensibleEnumeration"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativesFairValueLineItems_75f6725e-25ba-4abb-816f-74d32ed34636" xlink:to="loc_us-gaap_DerivativeLiabilityCurrentStatementOfFinancialPositionExtensibleEnumeration_c6d208fe-f869-43ac-a58d-d284070dbd61" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeLiabilityNoncurrentStatementOfFinancialPositionExtensibleEnumeration_4ecd83b2-b6a1-484c-be7c-fd88d9104974" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DerivativeLiabilityNoncurrentStatementOfFinancialPositionExtensibleEnumeration"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativesFairValueLineItems_75f6725e-25ba-4abb-816f-74d32ed34636" xlink:to="loc_us-gaap_DerivativeLiabilityNoncurrentStatementOfFinancialPositionExtensibleEnumeration_4ecd83b2-b6a1-484c-be7c-fd88d9104974" xlink:type="arc" order="9"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.blackbaud.com/role/DerivativeInstrumentsEffectsofDerivativeInstrumentsinCashFlowHedgingRelationshipsDetails" xlink:type="simple" xlink:href="blkb-20240930.xsd#DerivativeInstrumentsEffectsofDerivativeInstrumentsinCashFlowHedgingRelationshipsDetails"/>
  <link:definitionLink xlink:role="http://www.blackbaud.com/role/DerivativeInstrumentsEffectsofDerivativeInstrumentsinCashFlowHedgingRelationshipsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentsGainLossLineItems_126ce57b-232a-46c1-9fb5-4af23228b975" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DerivativeInstrumentsGainLossLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable_167e96ef-70b5-4646-b2f1-b43a42d1a347" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossLineItems_126ce57b-232a-46c1-9fb5-4af23228b975" xlink:to="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable_167e96ef-70b5-4646-b2f1-b43a42d1a347" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_c6aad0be-1b4b-40ec-b683-ae43f407d7f6" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DerivativeInstrumentRiskAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable_167e96ef-70b5-4646-b2f1-b43a42d1a347" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_c6aad0be-1b4b-40ec-b683-ae43f407d7f6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_c6aad0be-1b4b-40ec-b683-ae43f407d7f6_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_c6aad0be-1b4b-40ec-b683-ae43f407d7f6" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_c6aad0be-1b4b-40ec-b683-ae43f407d7f6_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_ce4edf74-4b13-4a4c-8d97-96e4064f548e" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_c6aad0be-1b4b-40ec-b683-ae43f407d7f6" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_ce4edf74-4b13-4a4c-8d97-96e4064f548e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestRateSwapMember_eb11111d-4c6e-4b73-b75c-30a490169d32" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_InterestRateSwapMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_ce4edf74-4b13-4a4c-8d97-96e4064f548e" xlink:to="loc_us-gaap_InterestRateSwapMember_eb11111d-4c6e-4b73-b75c-30a490169d32" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ForeignExchangeForwardMember_24551c7c-6a89-4c84-add1-a8b6f95ea02e" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ForeignExchangeForwardMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_ce4edf74-4b13-4a4c-8d97-96e4064f548e" xlink:to="loc_us-gaap_ForeignExchangeForwardMember_24551c7c-6a89-4c84-add1-a8b6f95ea02e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_23818d23-1653-4922-b955-21693ffeb7eb" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable_167e96ef-70b5-4646-b2f1-b43a42d1a347" xlink:to="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_23818d23-1653-4922-b955-21693ffeb7eb" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingRelationshipDomain_23818d23-1653-4922-b955-21693ffeb7eb_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_HedgingRelationshipDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_23818d23-1653-4922-b955-21693ffeb7eb" xlink:to="loc_us-gaap_HedgingRelationshipDomain_23818d23-1653-4922-b955-21693ffeb7eb_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingRelationshipDomain_0cc6b843-30ad-4712-b6c1-44bb998880d0" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_HedgingRelationshipDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_23818d23-1653-4922-b955-21693ffeb7eb" xlink:to="loc_us-gaap_HedgingRelationshipDomain_0cc6b843-30ad-4712-b6c1-44bb998880d0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashFlowHedgingMember_eebd9d82-1a4f-4740-8127-6e64f97095d1" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CashFlowHedgingMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HedgingRelationshipDomain_0cc6b843-30ad-4712-b6c1-44bb998880d0" xlink:to="loc_us-gaap_CashFlowHedgingMember_eebd9d82-1a4f-4740-8127-6e64f97095d1" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetInvestmentHedgingMember_f74f9ce1-79d9-4f9c-851c-3b171649d885" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_NetInvestmentHedgingMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HedgingRelationshipDomain_0cc6b843-30ad-4712-b6c1-44bb998880d0" xlink:to="loc_us-gaap_NetInvestmentHedgingMember_f74f9ce1-79d9-4f9c-851c-3b171649d885" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GainLossOnDerivativeInstrumentsNetPretax_86ec4fc3-0a3d-48f6-98e5-1fa14095f88d" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_GainLossOnDerivativeInstrumentsNetPretax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossLineItems_126ce57b-232a-46c1-9fb5-4af23228b975" xlink:to="loc_us-gaap_GainLossOnDerivativeInstrumentsNetPretax_86ec4fc3-0a3d-48f6-98e5-1fa14095f88d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentsGainLossReclassifiedFromAccumulatedOCIIntoIncomeEffectivePortionNet_e79a356e-e340-41e5-94aa-6bba36eb4419" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DerivativeInstrumentsGainLossReclassifiedFromAccumulatedOCIIntoIncomeEffectivePortionNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossLineItems_126ce57b-232a-46c1-9fb5-4af23228b975" xlink:to="loc_us-gaap_DerivativeInstrumentsGainLossReclassifiedFromAccumulatedOCIIntoIncomeEffectivePortionNet_e79a356e-e340-41e5-94aa-6bba36eb4419" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentGainLossReclassifiedFromAociIntoIncomeEffectivePortionStatementOfIncomeOrComprehensiveIncomeExtensibleEnumeration_d2666b93-efab-43f3-8244-cf9bea6354a2" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DerivativeInstrumentGainLossReclassifiedFromAociIntoIncomeEffectivePortionStatementOfIncomeOrComprehensiveIncomeExtensibleEnumeration"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossLineItems_126ce57b-232a-46c1-9fb5-4af23228b975" xlink:to="loc_us-gaap_DerivativeInstrumentGainLossReclassifiedFromAociIntoIncomeEffectivePortionStatementOfIncomeOrComprehensiveIncomeExtensibleEnumeration_d2666b93-efab-43f3-8244-cf9bea6354a2" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.blackbaud.com/role/CommitmentsandContingenciesDetails" xlink:type="simple" xlink:href="blkb-20240930.xsd#CommitmentsandContingenciesDetails"/>
  <link:definitionLink xlink:role="http://www.blackbaud.com/role/CommitmentsandContingenciesDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermPurchaseCommitmentLineItems_92378360-2ef5-4e24-b713-8f2886a17d44" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LongTermPurchaseCommitmentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermPurchaseCommitmentTable_dd99aefe-7c54-4e23-b0e0-d02f23dc7daf" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LongTermPurchaseCommitmentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_LongTermPurchaseCommitmentLineItems_92378360-2ef5-4e24-b713-8f2886a17d44" xlink:to="loc_us-gaap_LongTermPurchaseCommitmentTable_dd99aefe-7c54-4e23-b0e0-d02f23dc7daf" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermPurchaseCommitmentByCategoryOfItemPurchasedAxis_6c1b1590-b1db-4a5f-98c5-a77d61334f8f" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LongTermPurchaseCommitmentByCategoryOfItemPurchasedAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LongTermPurchaseCommitmentTable_dd99aefe-7c54-4e23-b0e0-d02f23dc7daf" xlink:to="loc_us-gaap_LongTermPurchaseCommitmentByCategoryOfItemPurchasedAxis_6c1b1590-b1db-4a5f-98c5-a77d61334f8f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermPurchaseCommitmentCategoryOfItemPurchasedDomain_6c1b1590-b1db-4a5f-98c5-a77d61334f8f_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LongTermPurchaseCommitmentCategoryOfItemPurchasedDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongTermPurchaseCommitmentByCategoryOfItemPurchasedAxis_6c1b1590-b1db-4a5f-98c5-a77d61334f8f" xlink:to="loc_us-gaap_LongTermPurchaseCommitmentCategoryOfItemPurchasedDomain_6c1b1590-b1db-4a5f-98c5-a77d61334f8f_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermPurchaseCommitmentCategoryOfItemPurchasedDomain_2ac7e71d-8bc7-407f-8525-a072ad76cabc" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LongTermPurchaseCommitmentCategoryOfItemPurchasedDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongTermPurchaseCommitmentByCategoryOfItemPurchasedAxis_6c1b1590-b1db-4a5f-98c5-a77d61334f8f" xlink:to="loc_us-gaap_LongTermPurchaseCommitmentCategoryOfItemPurchasedDomain_2ac7e71d-8bc7-407f-8525-a072ad76cabc" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_blkb_ThirdpartyTechnologyMember_a61ad8e8-dc32-4934-8109-790862531d38" xlink:href="blkb-20240930.xsd#blkb_ThirdpartyTechnologyMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongTermPurchaseCommitmentCategoryOfItemPurchasedDomain_2ac7e71d-8bc7-407f-8525-a072ad76cabc" xlink:to="loc_blkb_ThirdpartyTechnologyMember_a61ad8e8-dc32-4934-8109-790862531d38" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_blkb_LongtermPurchaseCommitmentRemainingMinimumAmountCommitted_66ba9595-b2b4-4d15-9b30-8a153acb915c" xlink:href="blkb-20240930.xsd#blkb_LongtermPurchaseCommitmentRemainingMinimumAmountCommitted"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongTermPurchaseCommitmentLineItems_92378360-2ef5-4e24-b713-8f2886a17d44" xlink:to="loc_blkb_LongtermPurchaseCommitmentRemainingMinimumAmountCommitted_66ba9595-b2b4-4d15-9b30-8a153acb915c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingenciesLineItems_fc7ab2d2-8cda-4f98-a554-b9456e5e6fca" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LossContingenciesLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingenciesTable_e118778f-c5a2-494b-96d6-5c2a81c5593f" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LossContingenciesTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_LossContingenciesLineItems_fc7ab2d2-8cda-4f98-a554-b9456e5e6fca" xlink:to="loc_us-gaap_LossContingenciesTable_e118778f-c5a2-494b-96d6-5c2a81c5593f" xlink:type="arc" order="2" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_261edfe7-488d-4730-8095-e2ba4c26a665" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LossContingenciesTable_e118778f-c5a2-494b-96d6-5c2a81c5593f" xlink:to="loc_srt_RangeAxis_261edfe7-488d-4730-8095-e2ba4c26a665" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_261edfe7-488d-4730-8095-e2ba4c26a665_default" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_261edfe7-488d-4730-8095-e2ba4c26a665" xlink:to="loc_srt_RangeMember_261edfe7-488d-4730-8095-e2ba4c26a665_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_f6dbb790-10ca-44e3-8950-6401b1eee165" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_261edfe7-488d-4730-8095-e2ba4c26a665" xlink:to="loc_srt_RangeMember_f6dbb790-10ca-44e3-8950-6401b1eee165" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_cb081413-c752-43ec-a85a-e128793c1801" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_f6dbb790-10ca-44e3-8950-6401b1eee165" xlink:to="loc_srt_MinimumMember_cb081413-c752-43ec-a85a-e128793c1801" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_e01932c5-a500-4c15-9f14-6809eae229e2" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_f6dbb790-10ca-44e3-8950-6401b1eee165" xlink:to="loc_srt_MaximumMember_e01932c5-a500-4c15-9f14-6809eae229e2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_blkb_LiabilityInsuranceAmountTotal_228bd250-ddbb-4cec-9e51-79f9aa07a3e9" xlink:href="blkb-20240930.xsd#blkb_LiabilityInsuranceAmountTotal"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_fc7ab2d2-8cda-4f98-a554-b9456e5e6fca" xlink:to="loc_blkb_LiabilityInsuranceAmountTotal_228bd250-ddbb-4cec-9e51-79f9aa07a3e9" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_blkb_LiabilityInsuranceAmountDeductible_da20a117-13a9-4ef9-acbb-8260a9695e02" xlink:href="blkb-20240930.xsd#blkb_LiabilityInsuranceAmountDeductible"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_fc7ab2d2-8cda-4f98-a554-b9456e5e6fca" xlink:to="loc_blkb_LiabilityInsuranceAmountDeductible_da20a117-13a9-4ef9-acbb-8260a9695e02" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_blkb_SecurityIncidentNetPreTaxExpense_0a1915c3-4182-4273-a7e7-ebd2d0b75e2d" xlink:href="blkb-20240930.xsd#blkb_SecurityIncidentNetPreTaxExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_fc7ab2d2-8cda-4f98-a554-b9456e5e6fca" xlink:to="loc_blkb_SecurityIncidentNetPreTaxExpense_0a1915c3-4182-4273-a7e7-ebd2d0b75e2d" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_blkb_SecurityIncidentOngoingLegalFees_145023b7-1d79-4f0d-b6c9-5096ce4a592f" xlink:href="blkb-20240930.xsd#blkb_SecurityIncidentOngoingLegalFees"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_fc7ab2d2-8cda-4f98-a554-b9456e5e6fca" xlink:to="loc_blkb_SecurityIncidentOngoingLegalFees_145023b7-1d79-4f0d-b6c9-5096ce4a592f" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyAccrualCarryingValuePeriodIncreaseDecrease_e36e404c-9b12-4534-9fe6-e6d31180531a" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LossContingencyAccrualCarryingValuePeriodIncreaseDecrease"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_fc7ab2d2-8cda-4f98-a554-b9456e5e6fca" xlink:to="loc_us-gaap_LossContingencyAccrualCarryingValuePeriodIncreaseDecrease_e36e404c-9b12-4534-9fe6-e6d31180531a" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_blkb_SecurityIncidentNetCashOutlays_40d5b2e9-0ef8-4436-87d7-70c9783d599c" xlink:href="blkb-20240930.xsd#blkb_SecurityIncidentNetCashOutlays"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_fc7ab2d2-8cda-4f98-a554-b9456e5e6fca" xlink:to="loc_blkb_SecurityIncidentNetCashOutlays_40d5b2e9-0ef8-4436-87d7-70c9783d599c" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_blkb_SecurityIncidentPenalty_46b3d847-0a5c-4d3b-84bd-44129129086c" xlink:href="blkb-20240930.xsd#blkb_SecurityIncidentPenalty"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_fc7ab2d2-8cda-4f98-a554-b9456e5e6fca" xlink:to="loc_blkb_SecurityIncidentPenalty_46b3d847-0a5c-4d3b-84bd-44129129086c" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_blkb_SecurityIncidentExpectedCost_94aeeafd-2d78-498a-8629-599859206396" xlink:href="blkb-20240930.xsd#blkb_SecurityIncidentExpectedCost"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_fc7ab2d2-8cda-4f98-a554-b9456e5e6fca" xlink:to="loc_blkb_SecurityIncidentExpectedCost_94aeeafd-2d78-498a-8629-599859206396" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_blkb_ExpectedNetCashOutlaysForOngoingLegalFees_8c62d20b-e7ba-4afb-965b-59c3fce9a8a4" xlink:href="blkb-20240930.xsd#blkb_ExpectedNetCashOutlaysForOngoingLegalFees"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_fc7ab2d2-8cda-4f98-a554-b9456e5e6fca" xlink:to="loc_blkb_ExpectedNetCashOutlaysForOngoingLegalFees_8c62d20b-e7ba-4afb-965b-59c3fce9a8a4" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyAccrualAtCarryingValue_9a1ad4e5-8e81-4c83-b56c-77be449df99b" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LossContingencyAccrualAtCarryingValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_fc7ab2d2-8cda-4f98-a554-b9456e5e6fca" xlink:to="loc_us-gaap_LossContingencyAccrualAtCarryingValue_9a1ad4e5-8e81-4c83-b56c-77be449df99b" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyNumberOfPlaintiffs_666d1295-baf4-427f-9a6f-efb682aeb269" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LossContingencyNumberOfPlaintiffs"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_fc7ab2d2-8cda-4f98-a554-b9456e5e6fca" xlink:to="loc_us-gaap_LossContingencyNumberOfPlaintiffs_666d1295-baf4-427f-9a6f-efb682aeb269" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyPendingClaimsNumber_711191f9-dd6c-41dc-8a04-49d0b6bab19d" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LossContingencyPendingClaimsNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_fc7ab2d2-8cda-4f98-a554-b9456e5e6fca" xlink:to="loc_us-gaap_LossContingencyPendingClaimsNumber_711191f9-dd6c-41dc-8a04-49d0b6bab19d" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_blkb_SecurityIncidentSubrogationClaimsNumber_af243dd3-903e-4a08-95da-3b5247ff5f72" xlink:href="blkb-20240930.xsd#blkb_SecurityIncidentSubrogationClaimsNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_fc7ab2d2-8cda-4f98-a554-b9456e5e6fca" xlink:to="loc_blkb_SecurityIncidentSubrogationClaimsNumber_af243dd3-903e-4a08-95da-3b5247ff5f72" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_blkb_SecurityIncidentNumberOfStateAttorneysGeneral_86eb7aff-e76b-46ef-b519-1527c4dac1f6" xlink:href="blkb-20240930.xsd#blkb_SecurityIncidentNumberOfStateAttorneysGeneral"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_fc7ab2d2-8cda-4f98-a554-b9456e5e6fca" xlink:to="loc_blkb_SecurityIncidentNumberOfStateAttorneysGeneral_86eb7aff-e76b-46ef-b519-1527c4dac1f6" xlink:type="arc" order="13"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.blackbaud.com/role/StockholdersEquityDetails" xlink:type="simple" xlink:href="blkb-20240930.xsd#StockholdersEquityDetails"/>
  <link:definitionLink xlink:role="http://www.blackbaud.com/role/StockholdersEquityDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementLineItems_91f8d7c1-16a5-4144-ba65-bd20705991e5" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StatementLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementTable_2a1edd14-1861-4227-a2d0-3c750a750250" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StatementTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_91f8d7c1-16a5-4144-ba65-bd20705991e5" xlink:to="loc_us-gaap_StatementTable_2a1edd14-1861-4227-a2d0-3c750a750250" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AcceleratedShareRepurchasesDateAxis_4822e00f-bdf8-4eb5-b09d-8150c5809ed1" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AcceleratedShareRepurchasesDateAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_2a1edd14-1861-4227-a2d0-3c750a750250" xlink:to="loc_us-gaap_AcceleratedShareRepurchasesDateAxis_4822e00f-bdf8-4eb5-b09d-8150c5809ed1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AcceleratedShareRepurchasesDateDomain_4822e00f-bdf8-4eb5-b09d-8150c5809ed1_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AcceleratedShareRepurchasesDateDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AcceleratedShareRepurchasesDateAxis_4822e00f-bdf8-4eb5-b09d-8150c5809ed1" xlink:to="loc_us-gaap_AcceleratedShareRepurchasesDateDomain_4822e00f-bdf8-4eb5-b09d-8150c5809ed1_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AcceleratedShareRepurchasesDateDomain_65a6a910-f986-490c-91ff-c0e9223750dc" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AcceleratedShareRepurchasesDateDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AcceleratedShareRepurchasesDateAxis_4822e00f-bdf8-4eb5-b09d-8150c5809ed1" xlink:to="loc_us-gaap_AcceleratedShareRepurchasesDateDomain_65a6a910-f986-490c-91ff-c0e9223750dc" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_blkb_Q12024ASRMember_1a94599f-b550-46d8-96bb-c1cc23105351" xlink:href="blkb-20240930.xsd#blkb_Q12024ASRMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AcceleratedShareRepurchasesDateDomain_65a6a910-f986-490c-91ff-c0e9223750dc" xlink:to="loc_blkb_Q12024ASRMember_1a94599f-b550-46d8-96bb-c1cc23105351" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ShareRepurchaseProgramAxis_7dab2735-d17d-4dfb-84b6-fcf9e56ddd82" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_ShareRepurchaseProgramAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_2a1edd14-1861-4227-a2d0-3c750a750250" xlink:to="loc_srt_ShareRepurchaseProgramAxis_7dab2735-d17d-4dfb-84b6-fcf9e56ddd82" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ShareRepurchaseProgramDomain_7dab2735-d17d-4dfb-84b6-fcf9e56ddd82_default" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_ShareRepurchaseProgramDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ShareRepurchaseProgramAxis_7dab2735-d17d-4dfb-84b6-fcf9e56ddd82" xlink:to="loc_srt_ShareRepurchaseProgramDomain_7dab2735-d17d-4dfb-84b6-fcf9e56ddd82_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ShareRepurchaseProgramDomain_220f5134-7d00-4433-9849-e6eda813b97a" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_ShareRepurchaseProgramDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ShareRepurchaseProgramAxis_7dab2735-d17d-4dfb-84b6-fcf9e56ddd82" xlink:to="loc_srt_ShareRepurchaseProgramDomain_220f5134-7d00-4433-9849-e6eda813b97a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_blkb_December2021StockRepurchaseProgramMember_ba09a140-1333-40b2-a613-ce70b8a40288" xlink:href="blkb-20240930.xsd#blkb_December2021StockRepurchaseProgramMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ShareRepurchaseProgramDomain_220f5134-7d00-4433-9849-e6eda813b97a" xlink:to="loc_blkb_December2021StockRepurchaseProgramMember_ba09a140-1333-40b2-a613-ce70b8a40288" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_blkb_January2024StockRepurchaseProgramMember_591f3ae7-e20a-45a5-b922-ccbaae446289" xlink:href="blkb-20240930.xsd#blkb_January2024StockRepurchaseProgramMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ShareRepurchaseProgramDomain_220f5134-7d00-4433-9849-e6eda813b97a" xlink:to="loc_blkb_January2024StockRepurchaseProgramMember_591f3ae7-e20a-45a5-b922-ccbaae446289" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_blkb_July2024StockRepurchaseProgramMember_752d7670-57b4-498e-8a7e-df18bfc7c063" xlink:href="blkb-20240930.xsd#blkb_July2024StockRepurchaseProgramMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ShareRepurchaseProgramDomain_220f5134-7d00-4433-9849-e6eda813b97a" xlink:to="loc_blkb_July2024StockRepurchaseProgramMember_752d7670-57b4-498e-8a7e-df18bfc7c063" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_StockRepurchaseProgramAuthorizedAmount1_2813c9b2-3c90-42fa-ad44-c0be2bf23fb7" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_StockRepurchaseProgramAuthorizedAmount1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_91f8d7c1-16a5-4144-ba65-bd20705991e5" xlink:to="loc_srt_StockRepurchaseProgramAuthorizedAmount1_2813c9b2-3c90-42fa-ad44-c0be2bf23fb7" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AcceleratedShareRepurchasesCashOrStockSettlement_788f2670-a8b3-43f6-b3b1-af0fc9e76b6c" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AcceleratedShareRepurchasesCashOrStockSettlement"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_91f8d7c1-16a5-4144-ba65-bd20705991e5" xlink:to="loc_us-gaap_AcceleratedShareRepurchasesCashOrStockSettlement_788f2670-a8b3-43f6-b3b1-af0fc9e76b6c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AcceleratedShareRepurchasesSettlementPaymentOrReceipt_9bc6c9d1-d60f-403f-8641-bc3dbb675c7c" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AcceleratedShareRepurchasesSettlementPaymentOrReceipt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_91f8d7c1-16a5-4144-ba65-bd20705991e5" xlink:to="loc_us-gaap_AcceleratedShareRepurchasesSettlementPaymentOrReceipt_9bc6c9d1-d60f-403f-8641-bc3dbb675c7c" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TreasuryStockSharesAcquired_c722ec0b-80a1-4bec-a202-b437bae0cf7f" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_TreasuryStockSharesAcquired"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_91f8d7c1-16a5-4144-ba65-bd20705991e5" xlink:to="loc_us-gaap_TreasuryStockSharesAcquired_c722ec0b-80a1-4bec-a202-b437bae0cf7f" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_blkb_AcceleratedShareRepurchasesInitialDeliveryPercentageOfShares_f498e38c-b1fb-4347-bfc0-ac1df1d71a6d" xlink:href="blkb-20240930.xsd#blkb_AcceleratedShareRepurchasesInitialDeliveryPercentageOfShares"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_91f8d7c1-16a5-4144-ba65-bd20705991e5" xlink:to="loc_blkb_AcceleratedShareRepurchasesInitialDeliveryPercentageOfShares_f498e38c-b1fb-4347-bfc0-ac1df1d71a6d" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AcceleratedShareRepurchasesAdjustmentToRecordedAmount_8d0567e9-8d88-4797-a59e-2e69ffa06fdf" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AcceleratedShareRepurchasesAdjustmentToRecordedAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_91f8d7c1-16a5-4144-ba65-bd20705991e5" xlink:to="loc_us-gaap_AcceleratedShareRepurchasesAdjustmentToRecordedAmount_8d0567e9-8d88-4797-a59e-2e69ffa06fdf" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TreasuryStockValueAcquiredCostMethod_db9861c5-fc0b-439a-866a-e3104eae177b" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_TreasuryStockValueAcquiredCostMethod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_91f8d7c1-16a5-4144-ba65-bd20705991e5" xlink:to="loc_us-gaap_TreasuryStockValueAcquiredCostMethod_db9861c5-fc0b-439a-866a-e3104eae177b" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockRepurchaseProgramRemainingAuthorizedRepurchaseAmount1_057b36a2-d01e-4ccb-9d50-3a906b89c812" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StockRepurchaseProgramRemainingAuthorizedRepurchaseAmount1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_91f8d7c1-16a5-4144-ba65-bd20705991e5" xlink:to="loc_us-gaap_StockRepurchaseProgramRemainingAuthorizedRepurchaseAmount1_057b36a2-d01e-4ccb-9d50-3a906b89c812" xlink:type="arc" order="7"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.blackbaud.com/role/StockholdersEquityChangesinAccumulatedOtherComprehensiveLossbyComponentDetails" xlink:type="simple" xlink:href="blkb-20240930.xsd#StockholdersEquityChangesinAccumulatedOtherComprehensiveLossbyComponentDetails"/>
  <link:definitionLink xlink:role="http://www.blackbaud.com/role/StockholdersEquityChangesinAccumulatedOtherComprehensiveLossbyComponentDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementLineItems_c8d2d300-e22e-46be-bb97-334567da8d5b" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StatementLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementTable_1dbfcd97-b440-4826-bfe0-c45e960ad061" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StatementTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_c8d2d300-e22e-46be-bb97-334567da8d5b" xlink:to="loc_us-gaap_StatementTable_1dbfcd97-b440-4826-bfe0-c45e960ad061" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLocationAxis_72816f9f-c1cb-4a49-ac9e-9fe82a541cf7" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_OtherComprehensiveIncomeLocationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_1dbfcd97-b440-4826-bfe0-c45e960ad061" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLocationAxis_72816f9f-c1cb-4a49-ac9e-9fe82a541cf7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLocationDomain_72816f9f-c1cb-4a49-ac9e-9fe82a541cf7_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_OtherComprehensiveIncomeLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_OtherComprehensiveIncomeLocationAxis_72816f9f-c1cb-4a49-ac9e-9fe82a541cf7" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLocationDomain_72816f9f-c1cb-4a49-ac9e-9fe82a541cf7_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLocationDomain_ce6cac47-7da5-4f98-b7b3-f108f5a6323d" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_OtherComprehensiveIncomeLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_OtherComprehensiveIncomeLocationAxis_72816f9f-c1cb-4a49-ac9e-9fe82a541cf7" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLocationDomain_ce6cac47-7da5-4f98-b7b3-f108f5a6323d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashFlowHedgingMember_5abcc882-8a3c-4c44-88a6-a3c8614e5302" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CashFlowHedgingMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherComprehensiveIncomeLocationDomain_ce6cac47-7da5-4f98-b7b3-f108f5a6323d" xlink:to="loc_us-gaap_CashFlowHedgingMember_5abcc882-8a3c-4c44-88a6-a3c8614e5302" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedTranslationAdjustmentMember_3b1c5766-db51-4418-a1a6-098292a31c02" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AccumulatedTranslationAdjustmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherComprehensiveIncomeLocationDomain_ce6cac47-7da5-4f98-b7b3-f108f5a6323d" xlink:to="loc_us-gaap_AccumulatedTranslationAdjustmentMember_3b1c5766-db51-4418-a1a6-098292a31c02" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_blkb_AccumulatedOtherComprehensiveIncomeRollForward_54e96dda-0cfa-461b-88dd-396f67784c28" xlink:href="blkb-20240930.xsd#blkb_AccumulatedOtherComprehensiveIncomeRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_c8d2d300-e22e-46be-bb97-334567da8d5b" xlink:to="loc_blkb_AccumulatedOtherComprehensiveIncomeRollForward_54e96dda-0cfa-461b-88dd-396f67784c28" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax_9a1550e0-9d48-460d-9393-8a2040edc76d" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_blkb_AccumulatedOtherComprehensiveIncomeRollForward_54e96dda-0cfa-461b-88dd-396f67784c28" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax_9a1550e0-9d48-460d-9393-8a2040edc76d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossBeforeReclassificationsTax_ec2ebac7-012f-4904-87ac-e6e011c79a22" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_OtherComprehensiveIncomeLossBeforeReclassificationsTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_blkb_AccumulatedOtherComprehensiveIncomeRollForward_54e96dda-0cfa-461b-88dd-396f67784c28" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossBeforeReclassificationsTax_ec2ebac7-012f-4904-87ac-e6e011c79a22" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OciBeforeReclassificationsNetOfTaxAttributableToParent_0ffbd78f-bdce-461f-ab8a-d220e9bf3850" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_OciBeforeReclassificationsNetOfTaxAttributableToParent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_blkb_AccumulatedOtherComprehensiveIncomeRollForward_54e96dda-0cfa-461b-88dd-396f67784c28" xlink:to="loc_us-gaap_OciBeforeReclassificationsNetOfTaxAttributableToParent_0ffbd78f-bdce-461f-ab8a-d220e9bf3850" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodBeforeTax_5f1ef31f-c7cd-46e0-a772-4161ddf2d333" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodBeforeTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_blkb_AccumulatedOtherComprehensiveIncomeRollForward_54e96dda-0cfa-461b-88dd-396f67784c28" xlink:to="loc_us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodBeforeTax_5f1ef31f-c7cd-46e0-a772-4161ddf2d333" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossBeforeReclassificationTax_6d0aa3c9-ff03-42ee-bacd-198d97396a70" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossBeforeReclassificationTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_blkb_AccumulatedOtherComprehensiveIncomeRollForward_54e96dda-0cfa-461b-88dd-396f67784c28" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossBeforeReclassificationTax_6d0aa3c9-ff03-42ee-bacd-198d97396a70" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReclassificationFromAociCurrentPeriodNetOfTaxAttributableToParent_91c47d99-a238-44cb-a5f4-8bec7cfd2d53" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ReclassificationFromAociCurrentPeriodNetOfTaxAttributableToParent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_blkb_AccumulatedOtherComprehensiveIncomeRollForward_54e96dda-0cfa-461b-88dd-396f67784c28" xlink:to="loc_us-gaap_ReclassificationFromAociCurrentPeriodNetOfTaxAttributableToParent_91c47d99-a238-44cb-a5f4-8bec7cfd2d53" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent_fc224720-8aa4-4a9a-a402-e9f5cf6b07bc" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_blkb_AccumulatedOtherComprehensiveIncomeRollForward_54e96dda-0cfa-461b-88dd-396f67784c28" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent_fc224720-8aa4-4a9a-a402-e9f5cf6b07bc" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossForeignCurrencyTransactionAndTranslationAdjustmentNetOfTax_dc5cef91-8f02-42b3-8a27-1ef00522e224" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_OtherComprehensiveIncomeLossForeignCurrencyTransactionAndTranslationAdjustmentNetOfTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_blkb_AccumulatedOtherComprehensiveIncomeRollForward_54e96dda-0cfa-461b-88dd-396f67784c28" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossForeignCurrencyTransactionAndTranslationAdjustmentNetOfTax_dc5cef91-8f02-42b3-8a27-1ef00522e224" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax_f944b45e-c5f5-4864-b5c4-9ce0009ac5a2" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.blackbaud.com/role/RevenueRecognitionDetails" xlink:type="simple" xlink:href="blkb-20240930.xsd#RevenueRecognitionDetails"/>
  <link:definitionLink xlink:role="http://www.blackbaud.com/role/RevenueRecognitionDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_5e400827-0f7e-4e20-96c3-5f1a36b09eba" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable_67014f5d-a1d0-4e82-9de0-dc437c207d9e" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_5e400827-0f7e-4e20-96c3-5f1a36b09eba" xlink:to="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable_67014f5d-a1d0-4e82-9de0-dc437c207d9e" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionStartDateAxis_4dc6334f-cc53-4678-b461-99c4763bf521" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionStartDateAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable_67014f5d-a1d0-4e82-9de0-dc437c207d9e" xlink:to="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionStartDateAxis_4dc6334f-cc53-4678-b461-99c4763bf521" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligation_131fa9a9-377b-40b2-8fa7-5e63b32cee03" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RevenueRemainingPerformanceObligation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_5e400827-0f7e-4e20-96c3-5f1a36b09eba" xlink:to="loc_us-gaap_RevenueRemainingPerformanceObligation_131fa9a9-377b-40b2-8fa7-5e63b32cee03" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligationPercentage_be506b54-5e28-451d-8021-de5920c2c38c" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RevenueRemainingPerformanceObligationPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_5e400827-0f7e-4e20-96c3-5f1a36b09eba" xlink:to="loc_us-gaap_RevenueRemainingPerformanceObligationPercentage_be506b54-5e28-451d-8021-de5920c2c38c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionPeriod1_a2fe536b-128c-4dc4-a897-417891ae281d" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionPeriod1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_5e400827-0f7e-4e20-96c3-5f1a36b09eba" xlink:to="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionPeriod1_a2fe536b-128c-4dc4-a897-417891ae281d" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractWithCustomerLiabilityRevenueRecognized_4de64d7c-82a1-4bd2-b3e9-ce27d268e1b3" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ContractWithCustomerLiabilityRevenueRecognized"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_5e400827-0f7e-4e20-96c3-5f1a36b09eba" xlink:to="loc_us-gaap_ContractWithCustomerLiabilityRevenueRecognized_4de64d7c-82a1-4bd2-b3e9-ce27d268e1b3" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.blackbaud.com/role/RevenueRecognitionDetails_1" xlink:type="simple" xlink:href="blkb-20240930.xsd#RevenueRecognitionDetails_1"/>
  <link:definitionLink xlink:role="http://www.blackbaud.com/role/RevenueRecognitionDetails_1" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_5e400827-0f7e-4e20-96c3-5f1a36b09eba" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable_67014f5d-a1d0-4e82-9de0-dc437c207d9e" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_5e400827-0f7e-4e20-96c3-5f1a36b09eba" xlink:to="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable_67014f5d-a1d0-4e82-9de0-dc437c207d9e" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligation_131fa9a9-377b-40b2-8fa7-5e63b32cee03" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RevenueRemainingPerformanceObligation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_5e400827-0f7e-4e20-96c3-5f1a36b09eba" xlink:to="loc_us-gaap_RevenueRemainingPerformanceObligation_131fa9a9-377b-40b2-8fa7-5e63b32cee03" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligationPercentage_be506b54-5e28-451d-8021-de5920c2c38c" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RevenueRemainingPerformanceObligationPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_5e400827-0f7e-4e20-96c3-5f1a36b09eba" xlink:to="loc_us-gaap_RevenueRemainingPerformanceObligationPercentage_be506b54-5e28-451d-8021-de5920c2c38c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionPeriod1_a2fe536b-128c-4dc4-a897-417891ae281d" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionPeriod1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_5e400827-0f7e-4e20-96c3-5f1a36b09eba" xlink:to="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionPeriod1_a2fe536b-128c-4dc4-a897-417891ae281d" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractWithCustomerLiabilityRevenueRecognized_4de64d7c-82a1-4bd2-b3e9-ce27d268e1b3" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ContractWithCustomerLiabilityRevenueRecognized"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_5e400827-0f7e-4e20-96c3-5f1a36b09eba" xlink:to="loc_us-gaap_ContractWithCustomerLiabilityRevenueRecognized_4de64d7c-82a1-4bd2-b3e9-ce27d268e1b3" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.blackbaud.com/role/RevenueRecognitionDisaggregationofRevenuebyGeographyDetails" xlink:type="simple" xlink:href="blkb-20240930.xsd#RevenueRecognitionDisaggregationofRevenuebyGeographyDetails"/>
  <link:definitionLink xlink:role="http://www.blackbaud.com/role/RevenueRecognitionDisaggregationofRevenuebyGeographyDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisaggregationOfRevenueLineItems_07b12d2a-37e5-4443-aacd-93dfa4aa8663" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DisaggregationOfRevenueLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisaggregationOfRevenueTable_5234d12e-40a5-4fbb-862b-7d291ddd3339" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DisaggregationOfRevenueTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_07b12d2a-37e5-4443-aacd-93dfa4aa8663" xlink:to="loc_us-gaap_DisaggregationOfRevenueTable_5234d12e-40a5-4fbb-862b-7d291ddd3339" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_StatementGeographicalAxis_2e2ec610-147e-4660-8e04-6c708b1c2aa0" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_StatementGeographicalAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_5234d12e-40a5-4fbb-862b-7d291ddd3339" xlink:to="loc_srt_StatementGeographicalAxis_2e2ec610-147e-4660-8e04-6c708b1c2aa0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_SegmentGeographicalDomain_2e2ec610-147e-4660-8e04-6c708b1c2aa0_default" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_SegmentGeographicalDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_StatementGeographicalAxis_2e2ec610-147e-4660-8e04-6c708b1c2aa0" xlink:to="loc_srt_SegmentGeographicalDomain_2e2ec610-147e-4660-8e04-6c708b1c2aa0_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_SegmentGeographicalDomain_a00a2dd5-ec61-4cd9-b8c4-9a6c44d97a63" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_SegmentGeographicalDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_StatementGeographicalAxis_2e2ec610-147e-4660-8e04-6c708b1c2aa0" xlink:to="loc_srt_SegmentGeographicalDomain_a00a2dd5-ec61-4cd9-b8c4-9a6c44d97a63" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_country_US_f5ccb230-c54f-42ad-b9a1-9cc10d6a5cce" xlink:href="https://xbrl.sec.gov/country/2024/country-2024.xsd#country_US"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_a00a2dd5-ec61-4cd9-b8c4-9a6c44d97a63" xlink:to="loc_country_US_f5ccb230-c54f-42ad-b9a1-9cc10d6a5cce" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_country_GB_b4b21709-9b6c-43ca-98c1-f8da94c5239b" xlink:href="https://xbrl.sec.gov/country/2024/country-2024.xsd#country_GB"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_a00a2dd5-ec61-4cd9-b8c4-9a6c44d97a63" xlink:to="loc_country_GB_b4b21709-9b6c-43ca-98c1-f8da94c5239b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_blkb_OthercountriesMember_e558f4ae-fa9f-4e23-a3e4-2e35079bc284" xlink:href="blkb-20240930.xsd#blkb_OthercountriesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_a00a2dd5-ec61-4cd9-b8c4-9a6c44d97a63" xlink:to="loc_blkb_OthercountriesMember_e558f4ae-fa9f-4e23-a3e4-2e35079bc284" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_1617938f-7d1d-46f6-a185-de464060db55" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_07b12d2a-37e5-4443-aacd-93dfa4aa8663" xlink:to="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_1617938f-7d1d-46f6-a185-de464060db55" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.blackbaud.com/role/RevenueRecognitionDisaggregationofRevenuebyMarketGroupDetails" xlink:type="simple" xlink:href="blkb-20240930.xsd#RevenueRecognitionDisaggregationofRevenuebyMarketGroupDetails"/>
  <link:definitionLink xlink:role="http://www.blackbaud.com/role/RevenueRecognitionDisaggregationofRevenuebyMarketGroupDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisaggregationOfRevenueLineItems_2f4b5f89-b2d5-4698-8a53-88e3804defc8" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DisaggregationOfRevenueLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisaggregationOfRevenueTable_373bb822-f903-475f-85b9-ec49c78b0442" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DisaggregationOfRevenueTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_2f4b5f89-b2d5-4698-8a53-88e3804defc8" xlink:to="loc_us-gaap_DisaggregationOfRevenueTable_373bb822-f903-475f-85b9-ec49c78b0442" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_5e2447a0-b7c0-4174-8d8c-b8ffade84b3f" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StatementBusinessSegmentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_373bb822-f903-475f-85b9-ec49c78b0442" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_5e2447a0-b7c0-4174-8d8c-b8ffade84b3f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_5e2447a0-b7c0-4174-8d8c-b8ffade84b3f_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_5e2447a0-b7c0-4174-8d8c-b8ffade84b3f" xlink:to="loc_us-gaap_SegmentDomain_5e2447a0-b7c0-4174-8d8c-b8ffade84b3f_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_6d6b0b87-4ebe-47c7-8cce-036baf078b61" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_5e2447a0-b7c0-4174-8d8c-b8ffade84b3f" xlink:to="loc_us-gaap_SegmentDomain_6d6b0b87-4ebe-47c7-8cce-036baf078b61" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_blkb_SocialSectorMember_afc14b3f-4770-4e41-8979-cbd6fb57d300" xlink:href="blkb-20240930.xsd#blkb_SocialSectorMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_6d6b0b87-4ebe-47c7-8cce-036baf078b61" xlink:to="loc_blkb_SocialSectorMember_afc14b3f-4770-4e41-8979-cbd6fb57d300" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_blkb_CorporateSectorMember_96aa13bc-772d-4462-b0d8-e6e86f64efc6" xlink:href="blkb-20240930.xsd#blkb_CorporateSectorMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_6d6b0b87-4ebe-47c7-8cce-036baf078b61" xlink:to="loc_blkb_CorporateSectorMember_96aa13bc-772d-4462-b0d8-e6e86f64efc6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_892bd7a6-7be3-41bc-8d89-efdbb6982f59" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_2f4b5f89-b2d5-4698-8a53-88e3804defc8" xlink:to="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_892bd7a6-7be3-41bc-8d89-efdbb6982f59" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.blackbaud.com/role/RevenueRecognitionDisaggregationofRecurringRevenuebyTypeDetails" xlink:type="simple" xlink:href="blkb-20240930.xsd#RevenueRecognitionDisaggregationofRecurringRevenuebyTypeDetails"/>
  <link:definitionLink xlink:role="http://www.blackbaud.com/role/RevenueRecognitionDisaggregationofRecurringRevenuebyTypeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisaggregationOfRevenueLineItems_fbc3d27f-366a-40a4-9f33-641929241bda" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DisaggregationOfRevenueLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisaggregationOfRevenueTable_a41e42d6-2ad9-4a49-930c-7ae1342fb554" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DisaggregationOfRevenueTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_fbc3d27f-366a-40a4-9f33-641929241bda" xlink:to="loc_us-gaap_DisaggregationOfRevenueTable_a41e42d6-2ad9-4a49-930c-7ae1342fb554" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductOrServiceAxis_c3217561-fd79-49a3-a522-c242187644b6" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_ProductOrServiceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_a41e42d6-2ad9-4a49-930c-7ae1342fb554" xlink:to="loc_srt_ProductOrServiceAxis_c3217561-fd79-49a3-a522-c242187644b6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_c3217561-fd79-49a3-a522-c242187644b6_default" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ProductOrServiceAxis_c3217561-fd79-49a3-a522-c242187644b6" xlink:to="loc_srt_ProductsAndServicesDomain_c3217561-fd79-49a3-a522-c242187644b6_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_3800774f-e5a8-435a-97d6-47deda3f171a" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ProductOrServiceAxis_c3217561-fd79-49a3-a522-c242187644b6" xlink:to="loc_srt_ProductsAndServicesDomain_3800774f-e5a8-435a-97d6-47deda3f171a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_blkb_ContractualRecurringMember_2e9d16fe-11ce-4da0-ac6c-52eb5ef1c5d5" xlink:href="blkb-20240930.xsd#blkb_ContractualRecurringMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_3800774f-e5a8-435a-97d6-47deda3f171a" xlink:to="loc_blkb_ContractualRecurringMember_2e9d16fe-11ce-4da0-ac6c-52eb5ef1c5d5" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_blkb_TransactionalRecurringMember_272aac33-04f0-4544-8035-03a939dba8e7" xlink:href="blkb-20240930.xsd#blkb_TransactionalRecurringMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_3800774f-e5a8-435a-97d6-47deda3f171a" xlink:to="loc_blkb_TransactionalRecurringMember_272aac33-04f0-4544-8035-03a939dba8e7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_blkb_RecurringMember_03295146-32c5-46ee-82ef-dfc662cae16c" xlink:href="blkb-20240930.xsd#blkb_RecurringMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_3800774f-e5a8-435a-97d6-47deda3f171a" xlink:to="loc_blkb_RecurringMember_03295146-32c5-46ee-82ef-dfc662cae16c" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_6b071ecf-8586-4467-8c92-627e04e064d7" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_fbc3d27f-366a-40a4-9f33-641929241bda" xlink:to="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_6b071ecf-8586-4467-8c92-627e04e064d7" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.blackbaud.com/role/SubsequentEventsDetails" xlink:type="simple" xlink:href="blkb-20240930.xsd#SubsequentEventsDetails"/>
  <link:definitionLink xlink:role="http://www.blackbaud.com/role/SubsequentEventsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventLineItems_92baaccb-2424-4b64-95fe-00dc18d5ec7d" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SubsequentEventLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTable_cb0e061c-2f10-41ef-b7a0-da66d09c13da" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SubsequentEventTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_SubsequentEventLineItems_92baaccb-2424-4b64-95fe-00dc18d5ec7d" xlink:to="loc_us-gaap_SubsequentEventTable_cb0e061c-2f10-41ef-b7a0-da66d09c13da" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeAxis_5b40271d-3ef1-4fb1-8fc4-2445b7b4e14c" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SubsequentEventTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_SubsequentEventTable_cb0e061c-2f10-41ef-b7a0-da66d09c13da" xlink:to="loc_us-gaap_SubsequentEventTypeAxis_5b40271d-3ef1-4fb1-8fc4-2445b7b4e14c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_5b40271d-3ef1-4fb1-8fc4-2445b7b4e14c_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SubsequentEventTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_5b40271d-3ef1-4fb1-8fc4-2445b7b4e14c" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_5b40271d-3ef1-4fb1-8fc4-2445b7b4e14c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_279ef71b-cd64-4313-bb54-98402ebbb384" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SubsequentEventTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_5b40271d-3ef1-4fb1-8fc4-2445b7b4e14c" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_279ef71b-cd64-4313-bb54-98402ebbb384" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventMember_f0005368-5f35-4899-b19f-64cc36b002f8" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SubsequentEventMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventTypeDomain_279ef71b-cd64-4313-bb54-98402ebbb384" xlink:to="loc_us-gaap_SubsequentEventMember_f0005368-5f35-4899-b19f-64cc36b002f8" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AcceleratedShareRepurchasesDateAxis_195ae2a0-786c-4d04-9af6-84616d7413cc" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AcceleratedShareRepurchasesDateAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_SubsequentEventTable_cb0e061c-2f10-41ef-b7a0-da66d09c13da" xlink:to="loc_us-gaap_AcceleratedShareRepurchasesDateAxis_195ae2a0-786c-4d04-9af6-84616d7413cc" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AcceleratedShareRepurchasesDateDomain_195ae2a0-786c-4d04-9af6-84616d7413cc_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AcceleratedShareRepurchasesDateDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AcceleratedShareRepurchasesDateAxis_195ae2a0-786c-4d04-9af6-84616d7413cc" xlink:to="loc_us-gaap_AcceleratedShareRepurchasesDateDomain_195ae2a0-786c-4d04-9af6-84616d7413cc_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AcceleratedShareRepurchasesDateDomain_fdc2b3b2-4fd3-4018-a6a9-6be9be4dfe06" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AcceleratedShareRepurchasesDateDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AcceleratedShareRepurchasesDateAxis_195ae2a0-786c-4d04-9af6-84616d7413cc" xlink:to="loc_us-gaap_AcceleratedShareRepurchasesDateDomain_fdc2b3b2-4fd3-4018-a6a9-6be9be4dfe06" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_blkb_Q12024ASRMember_ab8dd5bd-91df-4497-88ec-9b0c3208f4d4" xlink:href="blkb-20240930.xsd#blkb_Q12024ASRMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AcceleratedShareRepurchasesDateDomain_fdc2b3b2-4fd3-4018-a6a9-6be9be4dfe06" xlink:to="loc_blkb_Q12024ASRMember_ab8dd5bd-91df-4497-88ec-9b0c3208f4d4" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_blkb_Q12024ASRSettlementMember_fc66364f-53be-4b0b-a7da-e5b0c17433b8" xlink:href="blkb-20240930.xsd#blkb_Q12024ASRSettlementMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AcceleratedShareRepurchasesDateDomain_fdc2b3b2-4fd3-4018-a6a9-6be9be4dfe06" xlink:to="loc_blkb_Q12024ASRSettlementMember_fc66364f-53be-4b0b-a7da-e5b0c17433b8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TreasuryStockSharesAcquired_52d13d21-cb74-4de1-a6ca-ebf1209ab9f6" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_TreasuryStockSharesAcquired"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventLineItems_92baaccb-2424-4b64-95fe-00dc18d5ec7d" xlink:to="loc_us-gaap_TreasuryStockSharesAcquired_52d13d21-cb74-4de1-a6ca-ebf1209ab9f6" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://xbrl.sec.gov/ecd/role/IndividualsOnly" xlink:type="simple" xlink:href="https://xbrl.sec.gov/ecd/2024/ecd-2024.xsd#IndividualsOnly"/>
  <link:definitionLink xlink:role="http://xbrl.sec.gov/ecd/role/IndividualsOnly" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_ecd_AllIndividualsMember" xlink:href="https://xbrl.sec.gov/ecd/2024/ecd-2024.xsd#ecd_AllIndividualsMember"/>
    <link:loc xlink:type="locator" xlink:label="loc_blkb_MichaelP.GianoniMember_81b95f7b-6709-400f-81cd-98ad0723b604" xlink:href="blkb-20240930.xsd#blkb_MichaelP.GianoniMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ecd_AllIndividualsMember" xlink:to="loc_blkb_MichaelP.GianoniMember_81b95f7b-6709-400f-81cd-98ad0723b604" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_blkb_AnthonyW.BoorMember_0d3cf6cc-345d-47c9-942e-9fd6584846d7" xlink:href="blkb-20240930.xsd#blkb_AnthonyW.BoorMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ecd_AllIndividualsMember" xlink:to="loc_blkb_AnthonyW.BoorMember_0d3cf6cc-345d-47c9-942e-9fd6584846d7" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://fasb.org/us-gaap/role/eedm/ExtensibleEnumerationLists" xlink:type="simple" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-roles-2024.xsd#eedm"/>
  <link:definitionLink xlink:role="http://fasb.org/us-gaap/role/eedm/ExtensibleEnumerationLists" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesCurrentAbstract" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LiabilitiesCurrentAbstract"/>
    <link:loc xlink:type="locator" xlink:label="loc_blkb_AccruedExpensesAndOtherCurrentLiabilities_fd8e16b8-ebdf-4a0a-8bfa-6b62a1286e56" xlink:href="blkb-20240930.xsd#blkb_AccruedExpensesAndOtherCurrentLiabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesCurrentAbstract" xlink:to="loc_blkb_AccruedExpensesAndOtherCurrentLiabilities_fd8e16b8-ebdf-4a0a-8bfa-6b62a1286e56" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesAbstract" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LiabilitiesAbstract"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebtCurrent" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LongTermDebtCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAbstract" xlink:to="loc_us-gaap_LongTermDebtCurrent" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebtNoncurrent" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LongTermDebtNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesAbstract" xlink:to="loc_us-gaap_LongTermDebtNoncurrent" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementAbstract" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_IncomeStatementAbstract"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementAbstract" xlink:to="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax" xlink:type="arc" order="1"/>
  </link:definitionLink>
</link:linkbase>
