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

    <schemaVersion>X0508</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2023-12-29</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0000100517</issuerCik>
        <issuerName>United Airlines Holdings, Inc.</issuerName>
        <issuerTradingSymbol>UAL</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001482973</rptOwnerCik>
            <rptOwnerName>Ward Laysha</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>P. O. BOX 66100 HDQLD</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>CHICAGO</rptOwnerCity>
            <rptOwnerState>IL</rptOwnerState>
            <rptOwnerZipCode>60666</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <aff10b5One>0</aff10b5One>

    <nonDerivativeTable></nonDerivativeTable>

    <derivativeTable>
        <derivativeTransaction>
            <securityTitle>
                <value>Share Units</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <footnoteId id="F1"/>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2023-12-29</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>752.29</value>
                    <footnoteId id="F2"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <footnoteId id="F3"/>
            </exerciseDate>
            <expirationDate>
                <footnoteId id="F3"/>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>752.29</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>8185.5</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeTransaction>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">The share units convert to shares of common stock on a 1-for-1 basis.</footnote>
        <footnote id="F2">Represents 2023 quarterly retainer fees that the Reporting Person elected to defer into a share account pursuant to the terms of the Company's 2006 Director Equity Incentive Plan (&quot;DEIP&quot;).</footnote>
        <footnote id="F3">The share units will be settled in common stock following the Reporting Person's separation from service in accordance with the terms of the DEIP.</footnote>
    </footnotes>

    <remarks>Exhibit List: Exhibit 24 - Authorization and Designation</remarks>

    <ownerSignature>
        <signatureName>/s/ James Cotton for Laysha Ward</signatureName>
        <signatureDate>2024-01-03</signatureDate>
    </ownerSignature>
</ownershipDocument>
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X0508
4
2023-12-29
0
0000100517
United Airlines Holdings, Inc.
UAL
0001482973
Ward Laysha
P. O. BOX 66100 HDQLD
CHICAGO
IL
60666
1
0
0
0
0
Share Units
2023-12-29
4
A
0
752.29
0
A
Common Stock
752.29
8185.5
D
The share units convert to shares of common stock on a 1-for-1 basis.
Represents 2023 quarterly retainer fees that the Reporting Person elected to defer into a share account pursuant to the terms of the Company's 2006 Director Equity Incentive Plan ("DEIP").
The share units will be settled in common stock following the Reporting Person's separation from service in accordance with the terms of the DEIP.
Exhibit List: Exhibit 24 - Authorization and Designation
/s/ James Cotton for Laysha Ward
2024-01-03