Sam Reinhart scored the game-winning goal at 15:55 of the third period and also had an assist for the Ice (35-35-2), who avenged a 5-3 loss to the Hitmen one night earlier on home ice in Cranbrook.
Jordyn Boyd also scored twice for Kootenay.
Brady Brassart had two goals for the Hitmen (46-20-5), whose winning streak ended at six games, and Calder Brooks and Zane Jones scored the others.
In a relief appearance, Ice goalie Mackenzie Skapski made nine saves to earn the victory. Wyatt Hoflin started in net for Kootenay and stopped just 6-of-9 shots he faced before being replaced by Skapski after Calgary’s third goal at 9:37 of the second period.
Mack Shields made 21 saves for the Hitmen in a losing cause.
The Ice went 1 for 2 with the man advantage, while the Hitmen scored once on four power-play chances.
It was the final game of the season for both squads.
The Hitmen finished third in the WHL’s Eastern Conference and will have home-ice advantage over the sixth place Swift Current Broncos (36-29-7) in the first round of the WHL playoffs, which start next Thursday.
The Ice placed eighth in the Eastern Conference and will take on the top seed Edmonton Oil Kings (51-15-6) starting on the road next Friday.