Buck led off the third with a drive off right-hander Justin Duchscherer into the left field bullpen. His next two homers came off left-handers. He hit a three-run homer into the second deck in left off Jerry Blevins in the fourth and connected against Craig Breslow for a solo shot in the sixth, off the center field restaurant.
He is the first catcher to hit three homers in a game since Victor Martinez accomplished the feat for Cleveland at Seattle on July 16, 2004.
Buck got a standing ovation from the crowd of 10,721 when he led off the eighth against Oakland righty Andrew Bailey, but he flied out to right. The fans remained standing as Buck ran back to the dugout.
It's the first three-run homer game and sixth multihomer game of Buck's career. It was the first three-homer game by a Blue Jays player since Adam Lind did it at Boston on Sept. 29, 2009.
Darrin Fletcher was the last Toronto catcher to hit three homers in a game, doing it Aug. 27, 2000, at Texas.