Filed Pursuant to Rule
424(b)(3)
Registration
No. 333-294414
PROSPECTUS
SUPPLEMENT
(to
Prospectus dated March 23, 2026)
FUSION
FUEL GREEN PLC
Up
to 2,403,387 Class A Ordinary Shares
This
prospectus supplement (this “Prospectus Supplement”) updates, amends, and supplements the prospectus dated March 23, 2026
(the “Prospectus”), which forms a part of Fusion Fuel Green PLC’s (the “Company,” “we,” “us,”
or “our”) Registration Statement on Form F-3 (File No. 333-294414) (the “Registration Statement”), relating to
the offer and resale from time to time by the selling shareholders named in the Prospectus (the “Selling Shareholders”) of
up to 2,403,387 Class A Ordinary Shares. The Selling Shareholders may sell such Class A Ordinary Shares at prevailing market prices,
at prices related to such prevailing market prices, at fixed prices or in negotiated transactions, as described under “Plan
of Distribution” in the Prospectus. Capitalized terms used and not defined herein are as defined in the Prospectus.
We
are filing this Prospectus Supplement to update certain information in the Prospectus. On November 13, 2026, the Company entered
into separate Warrants Cancellation and Exchange Agreements, each dated as of November 13, 2026 (each, a “November 2026
Warrant Exchange Agreement” and collectively, the “November 2026 Warrant Exchange Agreements”), with each of Roxy Capital
Corp. (“Roxy Capital”), Bower Four Capital Corp. (“Bower Four”), Leede Financial Inc. ITF Anthony Milewski (“Milewski”),
RJL18 Capital LP (“RJL18”) and Daniel Farb (“Farb” and, together with Roxy Capital, Bower Four, Milewski and
RJL18, the “Warrant Holders”). The November 2026 Warrant Exchange Agreements provide for (i) the surrender and cancellation
of the Exchanged February 2026 Warrants (as defined below) held by the Warrant Holders and (ii) the exchange (the “November 2026
Warrant Exchange”) of such Exchanged February 2026 Warrants, on a one-for-one basis, for new warrants to purchase Class A Ordinary
Shares (the “New Warrants”), in reliance upon the exemption from registration provided by Section 3(a)(9) of the Securities
Act of 1933, as amended (the “Securities Act”).
The
“Exchanged February 2026 Warrants” consist of (i) 150% Price Warrants to purchase Class A Ordinary Shares at an exercise
price of $5.148 per share and (ii) 200% Price Warrants to purchase Class A Ordinary Shares at an exercise price of $6.864 per share,
each originally issued pursuant to the February 2026 Securities Purchase Agreement and expiring on February 20, 2029. The issuance of
the 150% Price Warrants and the 200% Price Warrants was reported in our Report on Form 6-K furnished to the U.S. Securities and Exchange
Commission (the “SEC”) on February 18, 2026.
Pursuant
to the November 2026 Warrant Exchange Agreements, 150% Price Warrants to purchase an aggregate of 285,168 Class A Ordinary Shares and
200% Price Warrants to purchase an aggregate of 285,168 Class A Ordinary Shares held by the Warrant Holders have been cancelled and the
Warrant Holders have released all rights and claims under or in respect of such Exchanged February 2026 Warrants (other than rights and
claims arising under the November 2026 Warrant Exchange Agreements). In exchange, the Company issued New Warrants to purchase an aggregate
of 570,336 Class A Ordinary Shares, consisting of a New Warrant to purchase 149,374 Class A Ordinary Shares issued to Roxy Capital, exercisable
until November 15, 2026; a New Warrant to purchase 108,636 Class A Ordinary Shares issued to Bower Four, exercisable until November
16, 2026; a New Warrant to purchase 135,794 Class A Ordinary Shares issued to Milewski, exercisable until November 20,
2026; a New Warrant to purchase 149,374 Class A Ordinary Shares issued to RJL18, exercisable until November 18, 2026; and a New
Warrant to purchase 27,158 Class A Ordinary Shares issued to Farb, exercisable until November 18, 2026.
The
New Warrants issued to Roxy Capital, Bower Four, Milewski, RJL18, and Farb have exercise prices of $0.52 per share, $0.51 per share,
$0.50 per share, $0.53 per share, and $0.54 per share, respectively. The New Warrants are exercisable solely for cash. To the extent
that the issuance of Class A Ordinary Shares upon exercise would cause a Warrant Holder to exceed its beneficial ownership limitation,
the Warrant Holder may elect to receive, in lieu of such shares, pre-funded warrants to purchase Class A Ordinary Shares (the “New
Pre-Funded Warrants”), in which case it will pay in cash the applicable exercise price less $0.0035 per share, and each New Pre-Funded
Warrant will have a remaining exercise price of $0.0035 per share.
Each
of the New Warrants and the New Pre-Funded Warrants may not be exercised to the extent that, after giving effect to such exercise, its
holder (together with any of its affiliates) would beneficially own in excess of the percentage of Class A Ordinary Shares outstanding
immediately after giving effect to such exercise initially elected by such holder (the “Beneficial Ownership Limitation”),
which is 4.99% in the case of Roxy Capital, 4.99% in the case of Bower Four, 9.99% in the case of Milewski, 4.99% in the case
of RJL18, and 4.99% in the case of Farb. The Beneficial Ownership Limitation may be raised or lowered to any other percentage not in
excess of 9.99%, at the option of each Warrant Holder, provided that any increase will only be effective upon 61 days’ prior written
notice to the Company. The number of Class A Ordinary Shares being offered for resale under the Prospectus, as supplemented by this Prospectus
Supplement, does not take into account any limitations on the exercise of the New Warrants and the New Pre-Funded Warrants.
If
all of the New Warrants were exercised for cash, the Company would receive aggregate gross proceeds of approximately $294,809.
The
Class A Ordinary Shares issuable upon exercise of the 150% Price Warrants and the 200% Price Warrants were registered for resale pursuant
to the Registration Statement. Because the New Warrants were issued in exchange for the Exchanged February 2026 Warrants on a one-for-one
basis, the Class A Ordinary Shares issuable upon exercise of the New Warrants and the New Pre-Funded Warrants (the “New Warrant
Shares”) remain covered by the Registration Statement, up to the number of Class A Ordinary Shares registered thereunder in respect
of the exchanged warrants and not previously sold. All references in the section entitled “Selling Shareholders” of
the Prospectus, as previously supplemented, to the 150% Price Warrants or the 200% Price Warrants held by the Warrant Holders shall refer
to the New Warrants, and all references to the shares issuable thereunder shall include the New Warrant Shares.
This
Prospectus Supplement is not complete without the Prospectus. This Prospectus Supplement should be read in conjunction with the Prospectus,
which is to be delivered with this Prospectus Supplement, and is qualified by reference thereto, except to the extent that the information
in this Prospectus Supplement expressly updates or supersedes the information contained in the Prospectus or in any document incorporated
by reference therein that was filed with the SEC before the date of this Prospectus Supplement.
The
Class A Ordinary Shares are listed on The Nasdaq Capital Market tier of The Nasdaq Stock Market LLC (“Nasdaq”) under the
symbol “HTOO”. The last reported sale price of the Class A Ordinary Shares on Nasdaq on November 12, 2026 was $1.15.
Investing
in our securities involves a high degree of risk. For a discussion of information that should be considered in connection with an investment
in our securities, see “Risk Factors” beginning on page 4 of the Prospectus and the risk factors contained in any
document incorporated by reference into the Prospectus and this Prospectus Supplement.
Neither
the Securities and Exchange Commission nor any state securities commission has approved or disapproved of these securities or determined
if the Prospectus or this Prospectus Supplement is truthful or complete. Any representation to the contrary is a criminal offense.
The
date of this Prospectus Supplement is November 13, 2026.
