Material Event (Form 8-K)

Item 8.01. Other Events.

On September 18, 2025 Atmos Energy Corporation ("Atmos Energy") entered into an underwriting agreement (the "Underwriting Agreement") with BNP Paribas Securities Corp., Credit Agricole Securities (USA) Inc., Mizuho Securities USA LLC and U.S. Bancorp Investments, Inc., as representatives of the several underwriters named in Schedule I thereto, with respect to the offering and sale in an underwritten public offering (the "Offering") by Atmos Energy of $600 million aggregate principal amount of its 5.450% Senior Notes due 2056 (the "Notes"). The Offering has been registered under the Securities Act of 1933, as amended (the "Securities Act"), pursuant to a registration statement on Form S-3(Registration No. 333-283563)of Atmos Energy (the "Registration Statement") and the prospectus supplement dated September 18, 2025, which was filed with the Securities and Exchange Commission pursuant to Rule 424(b) of the Securities Act on September 22, 2025. Legal opinions related to the Registration Statement are also filed herewith as Exhibits 5.1 and 5.2.

Atmos Energy expects to receive net proceeds, after the underwriting discount and estimated offering expenses payable by it, of approximately $589.8 million. The Offering is expected to close on or about October 1, 2025, subject to customary closing conditions.

The Notes will be issued pursuant to an indenture dated March 26, 2009 (the "Indenture") between Atmos Energy and U.S. Bank Trust Company, National Association, as successor in interest to U.S. Bank National Association, as trustee (the "Trustee"), to be modified by an Officers' Certificate setting forth the terms of the Notes (the "Officers' Certificate"), to be dated October 1, 2025 and delivered to the Trustee pursuant to Section 301 of the Indenture. The Notes will be represented by two global securities, a form of which is filed as an exhibit hereto. The form of the Officers' Certificate and the Underwriting Agreement are each also filed as an exhibit hereto.