The following year, Pietrangelo was loaned by his NHL team, the St. Louis Blues, to play for Team Canada in his second World Junior Championships in 2010. He was selected as an alternate captain to Patrice Cormier. In the final game of the round-robin, Pietrangelo scored a shorthanded game-tying goal against the United States to send the game to overtime. Canada eventually won in a shootout and earned a bye into the semi-final. Advancing to the gold medal game, Canada met the United States in a rematch, but lost 6–5 in overtime. Pietrangelo picked up several individual honours at the conclusion of the tournament. He was named a Tournament All-Star by the media, the Best Defenceman by the directorate and was selected by the coaching staff as one of Canada's top three players.