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

<!--XBRL Document Created with the Workiva Platform-->
<!--Copyright 2026 Workiva-->
<!--r:01a04434-49d7-7f09-af8b-408b626e9958,g:9972baf8-4f36-4a4b-b958-d50317f364fe-->
<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://carlylesecuredlending.com/role/Cover" xlink:type="simple" xlink:href="csl-20261016.xsd#Cover"/>
  <link:definitionLink xlink:role="http://carlylesecuredlending.com/role/Cover" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementLineItems_01a04434-49d7-7f55-a1a2-d475d59360d0" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityListingsTable_01a04434-49d7-710f-8046-6a97d9111ae8" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityListingsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_01a04434-49d7-7f55-a1a2-d475d59360d0" xlink:to="loc_dei_EntityListingsTable_01a04434-49d7-710f-8046-6a97d9111ae8" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentAxis_01a04434-49d7-7f3f-b3d3-ebdbb0f1e667" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_dei_EntityListingsTable_01a04434-49d7-710f-8046-6a97d9111ae8" xlink:to="loc_us-gaap_DebtInstrumentAxis_01a04434-49d7-7f3f-b3d3-ebdbb0f1e667" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_01a04434-49d7-7f3f-b3d3-ebdbb0f1e667_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentAxis_01a04434-49d7-7f3f-b3d3-ebdbb0f1e667" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_01a04434-49d7-7f3f-b3d3-ebdbb0f1e667_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_01a04434-49d7-7340-94e5-c9a5786cbccb" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentAxis_01a04434-49d7-7f3f-b3d3-ebdbb0f1e667" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_01a04434-49d7-7340-94e5-c9a5786cbccb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_csl_A820NotesDue2028Member_01a04434-49d7-7967-9a5f-b4db57f98c02" xlink:href="csl-20261016.xsd#csl_A820NotesDue2028Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_01a04434-49d7-7340-94e5-c9a5786cbccb" xlink:to="loc_csl_A820NotesDue2028Member_01a04434-49d7-7967-9a5f-b4db57f98c02" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_DocumentType_01a04434-49d7-70cf-8403-4990eb298dbc" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_DocumentType"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_01a04434-49d7-7f55-a1a2-d475d59360d0" xlink:to="loc_dei_DocumentType_01a04434-49d7-70cf-8403-4990eb298dbc" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_AmendmentFlag_01a04434-49d7-71f9-ba37-281d7a963b7e" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_AmendmentFlag"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_01a04434-49d7-7f55-a1a2-d475d59360d0" xlink:to="loc_dei_AmendmentFlag_01a04434-49d7-71f9-ba37-281d7a963b7e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_DocumentPeriodEndDate_01a04434-49d7-78cf-9b93-c25680df6a37" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_DocumentPeriodEndDate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_01a04434-49d7-7f55-a1a2-d475d59360d0" xlink:to="loc_dei_DocumentPeriodEndDate_01a04434-49d7-78cf-9b93-c25680df6a37" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityRegistrantName_01a04434-49d7-705e-91e7-34cb3505d8a9" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityRegistrantName"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_01a04434-49d7-7f55-a1a2-d475d59360d0" xlink:to="loc_dei_EntityRegistrantName_01a04434-49d7-705e-91e7-34cb3505d8a9" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityCentralIndexKey_01a04434-49d7-7b34-9d6f-6747d8f01872" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityCentralIndexKey"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_01a04434-49d7-7f55-a1a2-d475d59360d0" xlink:to="loc_dei_EntityCentralIndexKey_01a04434-49d7-7b34-9d6f-6747d8f01872" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityIncorporationStateCountryCode_01a04434-49d7-7ff3-89d7-6aaaef5bd693" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityIncorporationStateCountryCode"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_01a04434-49d7-7f55-a1a2-d475d59360d0" xlink:to="loc_dei_EntityIncorporationStateCountryCode_01a04434-49d7-7ff3-89d7-6aaaef5bd693" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityFileNumber_01a04434-49d7-7960-a4b2-99b84ad68e45" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityFileNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_01a04434-49d7-7f55-a1a2-d475d59360d0" xlink:to="loc_dei_EntityFileNumber_01a04434-49d7-7960-a4b2-99b84ad68e45" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityTaxIdentificationNumber_01a04434-49d7-7a5c-8932-3502df509f0d" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityTaxIdentificationNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_01a04434-49d7-7f55-a1a2-d475d59360d0" xlink:to="loc_dei_EntityTaxIdentificationNumber_01a04434-49d7-7a5c-8932-3502df509f0d" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityAddressAddressLine1_01a04434-49d7-7b92-a408-9879cae42834" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityAddressAddressLine1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_01a04434-49d7-7f55-a1a2-d475d59360d0" xlink:to="loc_dei_EntityAddressAddressLine1_01a04434-49d7-7b92-a408-9879cae42834" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityAddressCityOrTown_01a04434-49d7-73d9-ba21-e5fb9721a3ed" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityAddressCityOrTown"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_01a04434-49d7-7f55-a1a2-d475d59360d0" xlink:to="loc_dei_EntityAddressCityOrTown_01a04434-49d7-73d9-ba21-e5fb9721a3ed" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityAddressStateOrProvince_01a04434-49d7-76d9-b160-0da059c35ba1" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityAddressStateOrProvince"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_01a04434-49d7-7f55-a1a2-d475d59360d0" xlink:to="loc_dei_EntityAddressStateOrProvince_01a04434-49d7-76d9-b160-0da059c35ba1" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityAddressPostalZipCode_01a04434-49d7-729d-b3b4-6c4181b1ed75" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityAddressPostalZipCode"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_01a04434-49d7-7f55-a1a2-d475d59360d0" xlink:to="loc_dei_EntityAddressPostalZipCode_01a04434-49d7-729d-b3b4-6c4181b1ed75" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_CityAreaCode_01a04434-49d7-7953-8b19-41a1d0ab6f47" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_CityAreaCode"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_01a04434-49d7-7f55-a1a2-d475d59360d0" xlink:to="loc_dei_CityAreaCode_01a04434-49d7-7953-8b19-41a1d0ab6f47" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_LocalPhoneNumber_01a04434-49d7-7219-9e8d-f2f6d84795f4" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_LocalPhoneNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_01a04434-49d7-7f55-a1a2-d475d59360d0" xlink:to="loc_dei_LocalPhoneNumber_01a04434-49d7-7219-9e8d-f2f6d84795f4" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_WrittenCommunications_01a04434-49d7-71f0-9eee-632cfcd0ccac" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_WrittenCommunications"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_01a04434-49d7-7f55-a1a2-d475d59360d0" xlink:to="loc_dei_WrittenCommunications_01a04434-49d7-71f0-9eee-632cfcd0ccac" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_SolicitingMaterial_01a04434-49d7-747f-b221-b4db783eca7f" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_SolicitingMaterial"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_01a04434-49d7-7f55-a1a2-d475d59360d0" xlink:to="loc_dei_SolicitingMaterial_01a04434-49d7-747f-b221-b4db783eca7f" xlink:type="arc" order="15"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_PreCommencementTenderOffer_01a04434-49d7-7baf-9dfd-5e71d3cdd069" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_PreCommencementTenderOffer"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_01a04434-49d7-7f55-a1a2-d475d59360d0" xlink:to="loc_dei_PreCommencementTenderOffer_01a04434-49d7-7baf-9dfd-5e71d3cdd069" xlink:type="arc" order="16"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_PreCommencementIssuerTenderOffer_01a04434-49d7-78c3-964a-32d8c7a792af" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_PreCommencementIssuerTenderOffer"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_01a04434-49d7-7f55-a1a2-d475d59360d0" xlink:to="loc_dei_PreCommencementIssuerTenderOffer_01a04434-49d7-78c3-964a-32d8c7a792af" xlink:type="arc" order="17"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_Security12bTitle_01a04434-49d7-757e-9da9-2a3563d54a70" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_Security12bTitle"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_01a04434-49d7-7f55-a1a2-d475d59360d0" xlink:to="loc_dei_Security12bTitle_01a04434-49d7-757e-9da9-2a3563d54a70" xlink:type="arc" order="18"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_TradingSymbol_01a04434-49d7-7f2e-a300-7fde4029b337" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_TradingSymbol"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_01a04434-49d7-7f55-a1a2-d475d59360d0" xlink:to="loc_dei_TradingSymbol_01a04434-49d7-7f2e-a300-7fde4029b337" xlink:type="arc" order="19"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_SecurityExchangeName_01a04434-49d7-7348-8ddd-74ba8d4997f6" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_SecurityExchangeName"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_01a04434-49d7-7f55-a1a2-d475d59360d0" xlink:to="loc_dei_SecurityExchangeName_01a04434-49d7-7348-8ddd-74ba8d4997f6" xlink:type="arc" order="20"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityEmergingGrowthCompany_01a04434-49d7-71ef-b4ed-16f71779ede4" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityEmergingGrowthCompany"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_01a04434-49d7-7f55-a1a2-d475d59360d0" xlink:to="loc_dei_EntityEmergingGrowthCompany_01a04434-49d7-71ef-b4ed-16f71779ede4" xlink:type="arc" order="21"/>
  </link:definitionLink>
</link:linkbase>
