Un Atout was cut to 16-1 for the Supreme Novices' Hurdle after an effortless debut over timber in the Kells Maiden Hurdle at Navan.
A wide margin winner of his only bumper, he runs in the Gigginstown House Stud colours and Davy Russell set out to be positive on the four-year-old.
Useful rivals Some Article and Fickle Fortune closed up but Un Atout (1-2 favourite) kicked clear of the latter to win by four and three-quarter lengths.
"We knew he would probably have to make the running but he was brave in front to go and make it first time over hurdles," said Mullins
"He jumped like a chaser early on but his jumping flattened out as he sped up.
"He's probably more of a stayer and he's a chaser for the future.
"We'll see how he comes out of this and we'll definitely have a look at Christmas. He'll be entered in all the top novice races."