<SEC-DOCUMENT>0000824142-21-000100.txt : 20210518
<SEC-HEADER>0000824142-21-000100.hdr.sgml : 20210518
<ACCEPTANCE-DATETIME>20210518184004
ACCESSION NUMBER:		0000824142-21-000100
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20210516
FILED AS OF DATE:		20210518
DATE AS OF CHANGE:		20210518

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			Asbjornson Scott M
		CENTRAL INDEX KEY:			0001556286

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	000-18953
		FILM NUMBER:		21937744

	MAIL ADDRESS:	
		STREET 1:		3723 HOLLY TRAIL
		CITY:			LONGVIEW
		STATE:			TX
		ZIP:			75605

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			AAON, INC.
		CENTRAL INDEX KEY:			0000824142
		STANDARD INDUSTRIAL CLASSIFICATION:	AIR COND & WARM AIR HEATING EQUIP & COMM & INDL REFRIG EQUIP [3585]
		IRS NUMBER:				870448736
		STATE OF INCORPORATION:			NV
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		2425 SOUTH YUKON AVE.
		CITY:			TULSA
		STATE:			OK
		ZIP:			74107
		BUSINESS PHONE:		9185832266

	MAIL ADDRESS:	
		STREET 1:		2425 SOUTH YUKON AVE.
		CITY:			TULSA
		STATE:			OK
		ZIP:			74107

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	AAON INC
		DATE OF NAME CHANGE:	19920703

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	DIAMOND HEAD RESOURCES INC
		DATE OF NAME CHANGE:	19900808
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>wf-form4_162137750978071.xml
<DESCRIPTION>FORM 4
<TEXT>
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    <periodOfReport>2021-05-16</periodOfReport>

    <notSubjectToSection16>1</notSubjectToSection16>

    <issuer>
        <issuerCik>0000824142</issuerCik>
        <issuerName>AAON, INC.</issuerName>
        <issuerTradingSymbol>AAON</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001556286</rptOwnerCik>
            <rptOwnerName>Asbjornson Scott M</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>708 W. 79TH STREET S.</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>TULSA</rptOwnerCity>
            <rptOwnerState>OK</rptOwnerState>
            <rptOwnerZipCode>74132</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>Vice President, Finance &amp; CFO</officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
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            <securityTitle>
                <value>Common Stock, par value $.004</value>
            </securityTitle>
            <transactionDate>
                <value>2021-05-16</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>F</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
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                    <footnoteId id="F1"/>
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                <transactionPricePerShare>
                    <value>68.64</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
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                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
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                    <value>846726</value>
                </sharesOwnedFollowingTransaction>
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                </directOrIndirectOwnership>
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                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>Custodian for the benefit of his children</value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Common Stock, par value $.004</value>
            </securityTitle>
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                <sharesOwnedFollowingTransaction>
                    <value>2741</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>401(k) Plan</value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
    </nonDerivativeTable>

    <derivativeTable>
        <derivativeHolding>
            <securityTitle>
                <value>Stock Option (Right to Buy)</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>34.1</value>
            </conversionOrExercisePrice>
            <exerciseDate>
                <value>2021-05-16</value>
                <footnoteId id="F3"/>
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            <expirationDate>
                <value>2022-05-16</value>
                <footnoteId id="F4"/>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>6510.0</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>6510</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
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        </derivativeHolding>
        <derivativeHolding>
            <securityTitle>
                <value>Stock Option (Right to Buy)</value>
            </securityTitle>
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                <value>36.95</value>
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                <value>2021-05-16</value>
                <footnoteId id="F3"/>
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            <expirationDate>
                <value>2022-05-16</value>
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            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>15960.0</value>
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            </underlyingSecurity>
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                <sharesOwnedFollowingTransaction>
                    <value>15960</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
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        </derivativeHolding>
        <derivativeHolding>
            <securityTitle>
                <value>Stock Option (Right to Buy)</value>
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                <value>41.37</value>
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            <exerciseDate>
                <value>2021-05-16</value>
                <footnoteId id="F3"/>
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            <expirationDate>
                <value>2022-05-16</value>
                <footnoteId id="F4"/>
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                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>69000.0</value>
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                <sharesOwnedFollowingTransaction>
                    <value>69000</value>
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                    <value>D</value>
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        </derivativeHolding>
        <derivativeHolding>
            <securityTitle>
                <value>Stock Option (Right to Buy)</value>
            </securityTitle>
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                <value>44.22</value>
            </conversionOrExercisePrice>
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                <value>2021-03-11</value>
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            </expirationDate>
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            <securityTitle>
                <value>Stock Option (Right to Buy)</value>
            </securityTitle>
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                <value>73.36</value>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2021-05-16</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>D</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
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                    <value>11349</value>
                    <footnoteId id="F6"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>74.36</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
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            <exerciseDate>
                <value>2022-03-11</value>
            </exerciseDate>
            <expirationDate>
                <value>2031-03-11</value>
            </expirationDate>
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                <underlyingSecurityTitle>
                    <value>Common Stock</value>
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                <sharesOwnedFollowingTransaction>
                    <value>0</value>
                </sharesOwnedFollowingTransaction>
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            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
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        </derivativeTransaction>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">Tax withholding on vesting of Restricted Stock Awards due to retirement, effective May 16, 2021.</footnote>
        <footnote id="F2">Forfeiture of Restricted Stock Award (granted 3/11/2021) due to retirement, effective May 16, 2021.</footnote>
        <footnote id="F3">Date Exercisable (but not exercised) is accelerated upon retirement, effective May 16, 2021.</footnote>
        <footnote id="F4">Expiration date (1 year from retirement) is accelerated upon retirement, effective May 16, 2021.</footnote>
        <footnote id="F5">This stock award was granted (on 3/11/2020) under the Issuer's 2016 Long Term Incentive Plan and is exercisable ratably on each of the first five anniversaries of the date of the grant.</footnote>
        <footnote id="F6">Forfeiture of Stock Option Award (granted 3/11/2021) due to retirement, effective May 16, 2021.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>Scott M. Asbjornson</signatureName>
        <signatureDate>2021-05-18</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
