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

<!--XBRL Document Created with the Workiva Platform-->
<!--Copyright 2026 Workiva-->
<!--r:019ff178-cdc4-711f-a96c-a3e5a91cb720,g:7a2155bb-1a1d-4e45-8be1-a604e1a97727-->
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema" xmlns:link="http://www.xbrl.org/2003/linkbase" xmlns:ck0000017313="http://capitalsouthwest.com/20261102" attributeFormDefault="unqualified" elementFormDefault="qualified" targetNamespace="http://capitalsouthwest.com/20261102">
  <xs:import namespace="http://www.xbrl.org/2003/linkbase" schemaLocation="http://www.xbrl.org/2003/xbrl-linkbase-2003-12-31.xsd"/>
  <xs:import namespace="http://xbrl.sec.gov/cef-pre/2026" schemaLocation="https://xbrl.sec.gov/cef/2026/cef-2026_pre.xsd"/>
  <xs:import namespace="http://xbrl.sec.gov/dei-sub/2026" schemaLocation="https://xbrl.sec.gov/dei/2026/dei-sub-2026.xsd"/>
  <xs:annotation>
    <xs:appinfo/>
  </xs:annotation>
</xs:schema>
