6-K

UNITEDSTATES

SECURITIESAND EXCHANGE COMMISSION

Washington,D.C. 20549

FORM6-K

REPORTOF FOREIGN PRIVATE ISSUER PURSUANT TO RULE 13a-16 OR 15d-16

UNDERTHE SECURITIES EXCHANGE ACT OF 1934

For the month of: August, 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 August 27, 2025, Fusion Fuel Green PLC, an Irish public limited company (the “Company”), issued a press release announcing that the Company will release an investor presentation and video on the “Investors” section of its website at https://www.fusion-fuel.eu at 8:00 a.m. on Wednesday, September 17, 2025. A copy of the press release is furnished as Exhibit 99.1 to this report.

Forward-LookingStatements

The press release attached as Exhibit 99.1 hereto and the statements contained therein include “forward-looking statements” within the meaning of Section 27A of the U.S. Securities Act of 1933, as amended, and Section 21E of the U.S. Securities Exchange Act of 1934, as amended, which statements involve substantial risks and uncertainties. Forward-looking statements generally relate to future events or the Company’s future financial or operating performance. In some cases, you can identify these statements because they contain words such as “may,” “will,” “believes,” “expects,” “anticipates,” “estimates,” “projects,” “intends,” “should,” “seeks,” “future,” “continue,” “plan,” “target,” “predict,” “potential,” or the negative of such terms, or other comparable terminology that concern the Company’s expectations, strategy, plans, or intentions. Forward-looking statements relating to expectations about future results or events are based upon information available to the Company as of today’s date and are not guarantees of the future performance of the Company, and actual results may vary materially from the results and expectations discussed. The Company’s expectations and beliefs regarding these matters may not materialize, and actual results in future periods are subject to risks and uncertainties that could cause actual results to differ materially from those projected, including, without limitation, the risks and uncertainties described under Item 3. “Key Information – D. Risk Factors” and elsewhere in the Company’s Annual Report on Form 20-F filed with the U.S. Securities and Exchange Commission (the “SEC”) on May 9, 2025 (the “Annual Report”), and other filings with the SEC. Should any of these risks or uncertainties materialize, or should the underlying assumptions about the Company’s business and the commercial markets in which the Company operates prove incorrect, actual results may vary materially from those described as anticipated, estimated or expected in the Annual Report. All subsequent written and oral forward-looking statements concerning the Company or other matters and attributable to the Company or any person acting on its behalf are expressly qualified in their entirety by the cautionary statements above. The Company does not undertake any obligation to publicly update any of these forward-looking statements to reflect events or circumstances that may arise after the date hereof, except as required by law

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 99.1

FusionFuel Green PLC to Release a Mid-Year Investor Update on September 17, 2025

DUBLIN, Ireland – August 27, 2025 – Fusion Fuel Green PLC (NASDAQ: HTOO) (“Fusion Fuel” or the “Company”), a provider of integrated energy solutions, today announced that it will release an Investor Update Presentation and Video at 8:00 a.m. Eastern Time on Wednesday, September 17, 2025.

In the Investor Update Presentation and Video, management will provide investors with an update on the Company’s financial results and provide an update on the Company’s activities in both Al Shola Gas and BrightHy Solutions, as well as on other strategic developments.

The Investor Update Presentation and Video will be made available on Fusion Fuel´s Investors page on Fusion Fuel’s website at https://www.fusion-fuel.eu.

AboutFusion Fuel Green PLC

Fusion Fuel Green PLC (NASDAQ: HTOO) provides integrated energy engineering, distribution, and green hydrogen solutions through its Al Shola Gas and BrightHy Solutions platforms. With operations spanning LPG supply to hydrogen solutions, the Company supports decarbonization across industrial, residential, and commercial sectors. The Company is headquartered in Ireland with operations in Europe and the Middle East.

Forward-LookingStatements

This press release includes “forward-looking statements” within the meaning of Section 27A of the U.S. Securities Act of 1933, as amended, and Section 21E of the U.S. Securities Exchange Act of 1934, as amended, which statements involve substantial risks and uncertainties. Forward-looking statements generally relate to future events or the Company’s future financial or operating performance. In some cases, you can identify these statements because they contain words such as “may,” “will,” “believes,” “expects,” “anticipates,” “estimates,” “projects,” “intends,” “should,” “seeks,” “future,” “continue,” “plan,” “target,” “predict,” “potential,” or the negative of such terms, or other comparable terminology that concern the Company’s expectations, strategy, plans, or intentions. Forward-looking statements relating to expectations about future results or events are based upon information available to the Company as of today’s date and are not guarantees of the future performance of the Company, and actual results may vary materially from the results and expectations discussed. The Company’s expectations and beliefs regarding these matters may not materialize. Actual results in future periods are subject to risks and uncertainties that could cause actual results to differ materially from those projected, including, without limitation, the risks and uncertainties described under Item 3. “Key Information – D. Risk Factors” and elsewhere in the Company’s Annual Report on Form 20-F filed with the SEC on May 9, 2025 (the “Annual Report”), and other filings with the SEC. Should any of these risks or uncertainties materialize, or should the underlying assumptions about the Company’s business and the commercial markets in which the Company operates prove incorrect, actual results may vary materially from those described as anticipated, estimated, or expected in the Annual Report. All subsequent written and oral forward-looking statements concerning the Company or other matters and attributable to the Company or any person acting on its behalf are expressly qualified in their entirety by the cautionary statements above. The Company does not undertake any obligation to publicly update any of these forward-looking statements to reflect events or circumstances that may arise after the date hereof, except as required by law.

InvestorRelations Contact

ir@fusion-fuel.eu

www.fusion-fuel.eu