The Toronto Maple Leafs selected Percy as the 25th pick overall in the 2011 NHL Draft. From 2009 to 2013, the defenseman played 218 games in the Ontario Hockey League, posting 122 points and a +55 plus/minus rating. On to the AHL where between the 2011-12 and 2016-17 seasons he played a total of 214 games for the Wilkes-Barre/Scranton Penguins and Toronto Marlies, though only came away with 72 points in total. He skated in only 12 NHL games with the Leafs during the 2014-15 and 2015-16 seasons accumulating just 3 points.
Currently, Percy is a free agent.