Hamilton's Alex Green scored a 1-yard touchdown with 51 seconds remaining and Kenneth Allen hit the ensuing convert to tie the game at 25.
However, Calgary came roaring back and escaped with their 11th consecutive victory in controversial fashion. Bo Levi Mitchell heaved a pass toward the end zone intended for Anthony Parker, but Hamilton defensive back Courtney Stephen was called for pass interference on the penultimate play of the game.
Paredes then drilled an easy field goal to preserve the win for the league-leading Stampeders.
Mitchell went 19-of-34 for 279 yards, a touchdown, and an interception for Calgary, while Jeremiah Masoli finished 24-of-41 for 326 yards and an interception for Hamilton.