Turner Elson had the other goal for Red Deer (25-18-5), which got 36 saves from Patrik Bartosak.
Keegan Lowe scored for Edmonton (30-10-5), while Laurent Broissot made 25 stops in defeat.
Dieno snapped a 1-1 tie with his second of the night at 8:20 of the third period. Elson then made it 3-1 for Red Deer at 14:10 before Dieno completed his hat trick into an empty net with a minute remaining in regulation.
Red Deer finished the night 1-for-2 on the power play, while Edmonton was scoreless on its two chances.