UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 6-K

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

For the month of September 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.

☒ 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 on the purchase of treasury shares during the period from 22 to 25 September 2026

San Donato Milanese (Milan), 30 September 2026 – During the period from 22 to 25 September 2026, Eni acquired on the Euronext Milan no. 3,144,244 shares (equal to 0.10% of the share capital), at a weighted average price per share equal to 23.8531 euro, for a total consideration of 74,999,852.01 euro, within the second tranche of the treasury shares program approved by the Shareholders' Meeting on 6 May 2026, for the purpose of paying to the Shareholders an additional remuneration compared to the distribution of dividends, resolved by the same Shareholders’ Meeting.

Here below a synthesis of the purchase’s transactions on a daily basis:

From the start on 8 May 2026 of the buyback program, Eni acquired no. 73,139,727 shares (equal to 2.42% of the share capital) for a total consideration of 1,654,915,681.54 euro.

Considering the treasury shares already held and the purchases made, Eni holds n. 159,967,834 shares equal to 5.28% of the share capital.

Details of the daily transactions are reported below.