6-K

UNITEDSTATESSECURITIES AND EXCHANGE COMMISSION**** Washington, D.C. 20549

FORM6-K

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

For the month of: October, 2025.

Commission File Number: 001-39789

FusionFuel Green PLC

(Translation of registrant’s name into English)

9Pembroke Street Upper

DublinD02 KR83

Ireland

(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 ☐

On October 9, 2025, the board of directors of Fusion Fuel Green PLC, an Irish public limited company (the “Company”), approved Amendment No. 1 to the Fusion Fuel Green PLC 2021 Equity Incentive Plan (“Amendment No. 1”), to increase the maximum number of class A ordinary shares with a nominal value of $0.0035 each (“Class A Ordinary Shares”) available to be granted under the Fusion Fuel Green PLC 2021 Equity Incentive Plan by 1,971,428, to a total of 2,000,000 Class A Ordinary Shares. A copy of the Amendment No. 1 is furnished as Exhibit 10.1 to this report.

This Report on Form 6-K is incorporated by reference into the Company’s registration statements on Form F-3 (File Nos. 333-289429, 333-286198, 333-286202, 333-251990, 333-264714, and 333-276880) and Form S-8 (File No. 333-258543) and the prospectuses thereof and any prospectus supplements or amendments thereto.

SIGNATURES

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.

Exhibit 10.1

AMENDMENT NO. 1

TO

FUSION FUEL GREEN PLC 2021 EQUITY INCENTIVE PLAN

The Fusion Fuel Green PLC 2021 Equity Incentive Plan (the “Plan”) is hereby amended as follows:

The first sentence of Section 4.1 of the Plan is hereby amended in its entirety to read as follows:

“4.1. Subject to adjustment in accordance with Section 14 and subject to Section 4.3, no more than 2,000,000 Ordinary Shares shall be available for the grant of Awards under the Plan (the ‘Total Share Reserve’).”

Section 4.3 of the Plan is hereby amended in its entirety to read as follows:

“4.3. Subject to adjustment in accordance with Section 14, no more than 2,000,000 Ordinary Shares may be issued in the aggregate pursuant to the exercise of Incentive Share Options (the ‘ISO Limit’).”

Except as herein amended, the provisions of the Plan shall remain in full force and effect.

Effective as of October 9, 2025