<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0407</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2023-06-01</periodOfReport>

    <notSubjectToSection16>1</notSubjectToSection16>

    <issuer>
        <issuerCik>0000055772</issuerCik>
        <issuerName>KIMBALL INTERNATIONAL INC</issuerName>
        <issuerTradingSymbol>KBAL</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001616695</rptOwnerCik>
            <rptOwnerName>CONNOLLY PATRICK E</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>1600 ROYAL STREET</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>JASPER</rptOwnerCity>
            <rptOwnerState>IN</rptOwnerState>
            <rptOwnerZipCode>47546-2256</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <aff10b5One>0</aff10b5One>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>CLASS B COMMON STOCK</value>
            </securityTitle>
            <transactionDate>
                <value>2023-06-01</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>D</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>65160</value>
                </transactionShares>
                <transactionPricePerShare>
                    <footnoteId id="F1"/>
                    <footnoteId id="F2"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>0</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <derivativeTable></derivativeTable>

    <footnotes>
        <footnote id="F1">On June 1, 2023, pursuant to the Agreement and Plan of Merger, dated as of March 7, 2023 (the &quot;Merger Agreement&quot;), by and among Kimball International, Inc. (&quot;Kimball&quot;), HNI Corporation (&quot;HNI&quot;) and Ozark Merger Sub, Inc. (&quot;Merger Sub&quot;), Merger Sub merged with and into Kimball (the &quot;Merger&quot;), with Kimball surviving the Merger as a wholly-owned subsidiary of HNI.</footnote>
        <footnote id="F2">Pursuant to the Merger Agreement, each share of Kimball common stock issued and outstanding immediately prior to the effective time of the Merger was converted into the right to receive (A) $9.00 in cash, without interest (the &quot;Cash Consideration&quot;), and (B) 0.1301 (the &quot;Exchange Ratio&quot;) of a share of HNI common stock, par value $1.00. On May 31, 2023 (the last full trading day prior to the Merger), the closing price of one share of HNI common stock was $25.50.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>Mark W. Johnson, Attorney-in-Fact</signatureName>
        <signatureDate>2023-06-01</signatureDate>
    </ownerSignature>
</ownershipDocument>
