Gartner, Inc.

Item 1.01 Entry into a Material Definitive Agreement The information set forth in Item 8.01 below is incorporated by reference into this Item 1.01.

Item 2.03 Creation of a Direct Financial Obligation or an Obligation under an Off-Balance Sheet Arrangement of a Registrant The information set forth in Item 8.01 below is incorporated by reference into this Item 2.03.

Item 8.01. Other Events. On November 20, 2025, Gartner, Inc. (“Gartner”) completed the public offering and issuance of $350,000,000 aggregate principal amount of its 4.950% Senior Notes due 2031 (the “2031 Notes”) and $450,000,000 aggregate principal amount of its 5.600% Senior Notes due 2035 (the “2035 Notes” and, together with the 2031 Notes, the “Notes”). The Notes were sold pursuant to an Underwriting Agreement, dated November 13, 2025 (the “Underwriting Agreement”), between Gartner and J.P. Morgan Securities LLC, BofA Securities, Inc., Citigroup Global Markets Inc. and TD Securities (USA) LLC, as representatives of the underwriters named therein. The Notes were offered and sold pursuant to Gartner’s automatic shelf registration statement on Form S-3 (File No. 333-291447) and the prospectus included therein, filed with the Securities and Exchange Commission on November 12, 2025, and supplemented by the prospectus supplement dated November 13, 2025. The 2031 Notes were issued under the Indenture, dated as of November 20, 2025 (the “Base Indenture”), between Gartner and U.S. Bank Trust Company, National Association, as trustee (the “Trustee”), as supplemented by the First Supplemental Indenture, dated as of November 20, 2025 (the “First Supplemental Indenture”), between Gartner and the Trustee. The 2035 Notes were issued under the Base Indenture, as supplemented by the Second Supplemental Indenture, dated as of November 20, 2025 (the “Second Supplemental Indenture” and, together with the First Supplemental Indenture, the “Supplemental Indentures” and the Supplemental Indentures, together with the Base Indenture, the “Indenture”), between Gartner and the Trustee. The Notes are senior unsecured obligations of Gartner. The 2031 Notes will bear interest at a fixed rate of 4.950% per year, payable semi-annually in arrears on March 20 and September 20 of each year until their maturity on March 20, 2031. The 2035 Notes will bear interest at a fixed rate of 5.600% per year, payable semiannually in arrears on May 20 and November 20 of each year until their maturity on November 20, 2035. The Notes may be redeemed at Gartner’s option under certain circumstances, as described in the Indenture. The Indenture contains covenants that limit, among other things, Gartner’s ability to create liens, engage in sale and leaseback transactions and merge or consolidate with other entities, subject to a number of exceptions and qualifications. The Indenture also provides for events of default applicable to each series of Notes which, if any of them occur, would permit or require the principal and premium or interest, if any, on all of the then outstanding Notes of such series to be due and payable. Gartner received approximately $794.8 million in net proceeds, after deducting underwriting discounts but before offering expenses, from the sale of the Notes. Gartner intends to use a portion of the net proceeds from the offering of the notes to repay borrowings under its revolving credit facility and to pay related fees and expenses, with remaining amounts to be used for general corporate purposes, which may include, without limitation, potential repurchases of its common stock. The representations, warranties and covenants contained in the Underwriting Agreement were made only for purposes of such agreement and as of specific dates, were solely for the benefit of the parties to such agreement and are subject to certain limitations contained in the Underwriting Agreement. The foregoing description of the Underwriting Agreement, the Base Indenture and the Supplemental Indentures does not purport to be complete and is qualified in its entirety by reference to the full text of the Underwriting Agreement, the Base Indenture and the Supplemental Indentures (including the forms of the Notes), which are filed and incorporated by reference as Exhibits 1.1, 4.1, 4.2 and 4.3, hereto, respectively.