The son of Galileo, priced at 7/2, faced a challenge from Farhh - ridden by Frankie Dettori - in the closing stages but carried William Buick away to take the Group 1 race by half a length.
Third place went to Twice Over, winner in 2010.
"I have to say that was a fantastic training performance from John Gosden," Buick said. "To get the horse here in the shape he was in, all credit to John.
"He's got real quality and he showed today what a good horse he is. I have always had a lot of faith in this horse.
"He showed his versatility today and all being well he'll go for the King George again."
Gosden also enjoyed another victory at Sandown on Saturday as Trade Commissioner came in for him, while stable-mate Great Heavens won the Lancashire Oaks at Haydock.