Bargnani scored 24 points and Reggie Evans added a career-best 22 rebounds along with 12 points.
The Raptors grabbed a 33-18 lead after one period, increased their advantage to 19 at halftime and led by at least 10 the rest of the way.
Jerryd Bayless, playing his first game for Toronto since being acquired in a five-player deal with New Orleans, scored 13 points.
Andre Iguodala paced Philadelphia with 17 points. The 76ers have just three victories in 15 games this season and have won on the road only once.