<?xml version="1.0" encoding="utf-8"?>
<schema xmlns:ck0001678124="http://www.cioninvestments.com/20260401" xmlns="http://www.w3.org/2001/XMLSchema" xmlns:link="http://www.xbrl.org/2003/linkbase" xmlns:xbrldt="http://xbrl.org/2005/xbrldt" xmlns:xl="http://www.xbrl.org/2003/XLink" xmlns:xbrli="http://www.xbrl.org/2003/instance" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:negated="http://www.xbrl.org/2009/role/negated" xmlns:ref="http://www.xbrl.org/2006/ref" xmlns:deprecated="http://www.xbrl.org/2009/arcrole/fact-explanatoryFact" xmlns:dei="http://xbrl.sec.gov/dei/2025" xmlns:us-gaap="http://fasb.org/us-gaap/2025" xmlns:cef="http://xbrl.sec.gov/cef/2025" xmlns:cef-pre="http://xbrl.sec.gov/cef-pre/2025" xmlns:dtr-types="http://www.xbrl.org/dtr/type/2022-03-31" xmlns:dtr="http://www.xbrl.org/2009/dtr" xmlns:xbrldi="http://xbrl.org/2006/xbrldi" targetNamespace="http://www.cioninvestments.com/20260401" elementFormDefault="qualified">
  <!-- INTEGIX by Ez-XBRL -->
  <import namespace="http://www.xbrl.org/2003/instance" schemaLocation="http://www.xbrl.org/2003/xbrl-instance-2003-12-31.xsd"/>
  <import namespace="http://www.xbrl.org/2003/linkbase" schemaLocation="http://www.xbrl.org/2003/xbrl-linkbase-2003-12-31.xsd"/>
  <import namespace="http://xbrl.org/2005/xbrldt" schemaLocation="http://www.xbrl.org/2005/xbrldt-2005.xsd"/>
  <import namespace="http://xbrl.sec.gov/dei/2025" schemaLocation="https://xbrl.sec.gov/dei/2025/dei-2025.xsd"/>
  <import namespace="http://fasb.org/us-gaap/2025" schemaLocation="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd"/>
  <import namespace="http://xbrl.sec.gov/cef/2025" schemaLocation="https://xbrl.sec.gov/cef/2025/cef-2025.xsd"/>
  <import namespace="http://xbrl.sec.gov/cef-pre/2025" schemaLocation="https://xbrl.sec.gov/cef/2025/cef-2025_pre.xsd"/>
  <import namespace="http://www.xbrl.org/dtr/type/2022-03-31" schemaLocation="https://www.xbrl.org/dtr/type/2022-03-31/types.xsd"/>
  <annotation>
    <appinfo>
      <link:roleType roleURI="http://www.cioninvestments.com/role/Cover" id="Cover">
        <link:definition>0001 - Document - Document and Entity Information</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.cioninvestments.com/role/INVESTMENTOBJECTIVEANDPOLICIES" id="INVESTMENTOBJECTIVEANDPOLICIES">
        <link:definition>0002 - Disclosure - INVESTMENT OBJECTIVE AND POLICIES</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
      </link:roleType>
      <link:linkbaseRef xlink:type="simple" xlink:href="ck0001678124-20260401_pre.xml" xlink:role="http://www.xbrl.org/2003/role/presentationLinkbaseRef" xlink:arcrole="http://www.w3.org/1999/xlink/properties/linkbase"/>
      <link:linkbaseRef xlink:type="simple" xlink:href="ck0001678124-20260401_def.xml" xlink:role="http://www.xbrl.org/2003/role/definitionLinkbaseRef" xlink:arcrole="http://www.w3.org/1999/xlink/properties/linkbase"/>
      <link:linkbaseRef xlink:type="simple" xlink:href="ck0001678124-20260401_lab.xml" xlink:role="http://www.xbrl.org/2003/role/labelLinkbaseRef" xlink:arcrole="http://www.w3.org/1999/xlink/properties/linkbase"/>
    </appinfo>
  </annotation>
  <element name="ClassASharesCadexMember" id="ck0001678124_ClassASharesCadexMember" type="dtr-types:domainItemType" abstract="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" nillable="true"/>
  <element name="ClassCSharesCadcxMember" id="ck0001678124_ClassCSharesCadcxMember" type="dtr-types:domainItemType" abstract="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" nillable="true"/>
  <element name="ClassISharesCaduxMember" id="ck0001678124_ClassISharesCaduxMember" type="dtr-types:domainItemType" abstract="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" nillable="true"/>
  <element name="ClassLSharesCadwxMember" id="ck0001678124_ClassLSharesCadwxMember" type="dtr-types:domainItemType" abstract="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" nillable="true"/>
  <element name="ClassU2SharesCadsxMember" id="ck0001678124_ClassU2SharesCadsxMember" type="dtr-types:domainItemType" abstract="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" nillable="true"/>
  <element name="ClassUSharesCadzxMember" id="ck0001678124_ClassUSharesCadzxMember" type="dtr-types:domainItemType" abstract="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" nillable="true"/>
  <element name="ClassWSharesCadfxMember" id="ck0001678124_ClassWSharesCadfxMember" type="dtr-types:domainItemType" abstract="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" nillable="true"/>
  <element name="WellsCreditFacilityMember" id="ck0001678124_WellsCreditFacilityMember" type="dtr-types:domainItemType" abstract="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" nillable="true"/>
</schema>
