$400,000,000 3.950% Notes due 2029 $400,000,000 4.500% Notes due 2033 We are offering $400,000,000 aggregate principal amount of our 3.950% Notes due 2029 (the “2029 notes”) and $400,000,000 aggregateprincipal amount of our 4.500% Notes due 2033 (the “2033 notes” and, together with the 2029 notes, the “notes”). The 2029 notes will matureon February 1, 2029. We will pay interest on the 2029 notes on February 1 and August 1 of each year, commencing February 1, 2026. Intereston the 2029 notes will accrue from and including October 6, 2025. The 2033 notes will mature on February1, 2033. We will pay interest onthe 2033 notes on February 1 and August 1 of each year, commencing February1, 2026. Interest on the 2033 notes will accrue from andincluding October 6, 2025. We may redeem the notes of either series at our option, at any time in whole or from time to time in part, at theredemption prices described in this prospectus supplement under the caption “Description of Notes — Optional Redemption.” The notes will beour senior unsecured obligations. Realty Income Corporation, an S&P 500 company, isreal estate partner to the world’s leading companies. We are known as “TheMonthly Dividend Company” and have a mission to invest in people and places to deliver dependable monthly dividends that increase overtime. We are structured as a real estate investment trust, or REIT, requiring us annually to distribute at least 90% of our taxable income(excluding net capital gains) in the form of dividends to our stockholders. Our monthly dividends are supported by the cash flow generatedfrom real estate owned under long-term lease agreements with our commercial clients. As of June30, 2025, we owned or held interests in adiversified portfolio of 15,606 properties located in all 50 U.S. states, the United Kingdom, and seven other countries in Europe, withapproximately 346.3million square feet of leasable space leased to clients doing business in 91 separate industries.®® (1)Plus accrued interest, if any, from October 6, 2025, if settlement occurs after that date. Neither the U.S. Securities and Exchange Commission nor any state securities commission has approved or disapproved of these securities orpassed upon the adequacy or accuracy of this prospectus supplement or the accompanying prospectus. Any representation to the contrary is acriminal offense. Delivery of the notes will be made only in book-entry form through the facilities of The Depository Trust Company for the accounts of itsparticipants, including Clearstream Banking S.A. and Euroclear Bank SA/NV, as operator of the Euroclear System, against payment in NewYork, New York on or about October 6, 2025. TABLE OF CONTENTS Prospectus Supplement PagePROSPECTUS SUPPLEMENT SUMMARYS-1RISK FACTORSS-7FORWARD-LOOKING STATEMENTSS-14USE OF PROCEEDSS-16DESCRIPTION OF NOTESS-18SUPPLEMENTAL U.S. FEDERAL INCOME TAX CONSIDERATIONSS-29UNDERWRITING (CONFLICTS OF INTEREST)S-30LEGAL MATTERSS-36EXPERTSS-37INCORPORATION BY REFERENCES-38 Prospectus ABOUT THIS PROSPECTUS1THE COMPANY3RISK FACTORS4FORWARD-LOOKING STATEMENTS5USE OF PROCEEDS7DESCRIPTION OF DEBT SECURITIES8DESCRIPTION OF COMMON STOCK19GENERAL DESCRIPTION OF PREFERRED STOCK21DESCRIPTION OF OTHER SECURITIES35RESTRICTIONS ON OWNERSHIP AND TRANSFERS OF STOCK36CERTAIN PROVISIONS OF MARYLAND LAW AND OF OUR CHARTER AND BYLAWS39UNITED STATES FEDERAL INCOME TAX CONSIDERATIONS44PLAN OF DISTRIBUTION68LEGAL MATTERS69EXPERTS69WHERE YOU CAN FIND MORE INFORMATION70INCORPORATION BY REFERENCE71 You should rely only on the information contained or incorporated by reference in this prospectussupplement and the accompanying prospectus and, if applicable, any free writing prospectus we mayprovide you in connection with this offering. We have not, and the underwriters have not, authorized anyperson to provide you with different information. If anyone provides you with different or inconsistentinformation, you should not rely on it. We are not, and the underwriters are not, making an offer to sell thesesecurities or soliciting an offer to buy these securities in any jurisdiction where, or to any person to whom,the offer or sale of these securities is not permitted. You should assume that the information appearing inthis prospectus supplement, the accompanying prospectus, the documents incorporated by reference hereinor therein and, if applicable, any free writing prospectus we may provide you in connection with thisoffering is accurate only as of those documents’ respective dates or, in the case of documents incorporatedor deemed to be incorporated by reference herein or therein, as of the respective dates those documents werefiled with the U.S. Securities and Exchange Commission, or the SEC. Our business, financial condition,results of operations and prospects may have changed since those dates. This document is in two parts. The first part is this prospectus supplement, which adds to and updatesinformation contained in the accompanying prospectu