Amateur Graham Delaet fired a 65 to finish second at 11-under-par 273. Paul Danielson and Chris Cureton followed at 10-under-par 274.
McQuillan held a slim lead over Jon Turcott to start the day at Edmonton Country Club. He tallied a birdie and a bogey over his first two holes but picked up back-to-back birdies starting at the par-4 fifth to reach 14 under.
The 24-year-old found trouble with a bogey at the seventh but countered with a birdie at the eighth. McQuillan then pulled away from his challengers on the back nine with four birdies and a bogey for his first career victory on the Canadian Tour.
Delaet collected four birdies over his first nine holes. He added a birdie at the 10th but gave that shot back with a bogey at the 12th. Delaet recovered well with an eagle at the par-4 14th and added a birdie at the 16th to finish alone in second place.
Turcott posted a 73 to finish at 9-under-par 275. He was joined by Brock Mackenzie, Brian Unk, Peter Tomasulo, Jaime Gomez, Brian Guetz, Jim Lemon, Mike Belbin and Ben Bunny in a tie for fifth.