A David McMillan hat-trick gifted Dundalk their third FAI Cup in six years following a 4-2 win over Shamrock Rovers after extra-time at the Aviva Stadium.
McMillan, who became just the third player to score a hat-trick in an FAI Cup final, scored two goals in normal time and one in extra-time to upset Shamrock Rovers' dreams of an unbeaten league and cup double.
The victory marks the first trophy of the Filippo Giovagnoli era at Dundalk, who only entered management for the first time when Vinny Perth was sacked earlier this season.
Serving a touchline ban in the stands, Stephen Bradley could only watch on as his side fell to their first domestic defeat of the season.
Rovers initially took the lead on the 49th minute when a Jack Byrne corner was headed on to an unmarked Aaron Greene at the back post. The striker finished low under a jumping Gary Rodgers in the Dundalk goal.
Bradley's side looked like they might push on from there but Dundalk were soon ahead after a dramatic three minute double from McMillan.
The first was a superb finish inside the box, as McMillan beat Alan Mannus at the front post to equalise.
Two minutes later, he had a second from the penalty spot after Liam Scales brought down Dan Cleary from a corner.
However, the match had opened up for both sides and Rovers were immediately level again after two minutes.
Again, it was a dangerous corner from Byrne this time converted by the head of a high-rising Roberto Lopes.
Both sides had chances to win the game in normal time. McMillan's headed attempt for a hattrick was gathered by Mannus while Greene had a low shot parried away by Rodgers.
However, the biggest chance came for Lopes again in the 91st minute. Graham Burke whipped a low cross behind the defensive line to Lopes who nicked the ball just wide from within the six-yard box.
Moving into extra-time, Sean Hoare put Dundalk ahead with just nine minutes remaining and McMillan concluded a perfect night when he finished off a counter-attack and any remaining hopes Rovers had of a comeback.