6-K

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 6-K

REPORT OF FOREIGN PRIVATE ISSUER PURSUANT TORULE 13a-16 OR 15d-16 UNDER THE SECURITIES EXCHANGE ACT OF 1934

For the month of May 2026

Commission File Number 0001002242

Eni S.p.A.

(Translation of registrant’s name into English)

Piazzale Enrico Mattei 1 - 00144 Rome, Italy

(Address of principal executive office)

Indicate by check mark whether the registrant files or will file annual reports under cover of Form 20-F or Form 40-F.

x Form 20-F               ¨ Form 40-F

TABLE OF CONTENTS

SIGNATURE

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned, thereunto duly authorized.

Eni: report onthe purchase of treasury shares on 11 May 2026

San Donato Milanese(Milan), 20 May 2026 – On 11 May 2026, Eni acquired on the Euronext Milan no. 861,111 shares (equal to 0.03% of the share capital), at a weighted average price per share equal to 23.2258 euro, for a total consideration of 19,999,991.86 euro, within the first tranche of the treasury shares program approved by the Shareholders' Meeting on 6 May 2026, for the purpose of serving the 2026-2028 Long-Term Incentive Plan, resolved by the same Shareholders’ Meeting.

From the start on 8 May 2026 of the buyback program, Eni acquired no. 1,736,924 shares (equal to 0.06% of the share capital) for a total consideration of 39,999,969.95 euro.

Considering the treasury shares already held and the purchases made, Eni holds n. 88,565,031 shares equal to 2.92% of the share capital.

Details of the hourly transactions made during 11 May.

Company Contacts:

Press Office*:* Tel. +39.0252031875 – +39.0659822030

Freephone for shareholders (from Italy): 800940924

Freephone for shareholders (from abroad): + 80011223456

Switchboard: +39-0659821

ufficio.stampa@eni.com

segreteriasocietaria.azionisti@eni.com

investor.relations@eni.com

Web site: www.eni.com