The 9-2 shot kicked for the finish line with two furlongs remaining to beat the Newmarket Guineas winner by two and a half lengths with Blue De Vega third.
It was a second victory in the colts' classic for trainer Kevin Prendergast, who last won the race 40 years ago with Northern Treasure.
"I'd say he's as good a horse as I've had," said Prendergast, 83.
"But how far he will go I don't know. He was forced to go a bit early today as Frankie Dettori (Galileo Gold's jockey) was in a bit of bother on the inside, so he kicked and hoped for the best.
"I don't know where he will go next. The boss man (Sheikh Hamdan) makes the decision and we go along with it.
"He's in the Derby and the Irish Derby, so we'll see what he wants to do."
Galileo Gold, trained by Hugo Palmer, was looking to become the ninth horse in history to win both the Irish and English 2000 Guineas.
Detorri rode Galileo Gold to a surprise victory in the first classic of the 2016 Flat season, the 2000 Guineas at Newmarket on 30 April.
It gave Palmer his first victory in the race and saw the Irish and English double completed in successive years following the success of Gleneagles in 2015.
Awtaad, ridden by Chris Hayes, beat favourite Galileo Gold to win the Irish 2000 Guineas at the Curragh.