Mitch Holmberg had a goal and two assists for Spokane (9-3-0), while Tyler King, Collin Valcourt and Dylan Walchuk rounded out the scoring. Eric Williams earned the win with 24 saves.
Troy Bourke was the lone scorer for Prince George (5-7-1). Mac Engel stopped 17 shots for the Cougars.
The Chiefs went 1-for-2 on the power play, while Prince George was 1-for-4.
Bourke's first period power-play goal gave the Cougars the lead 12:19 into the first period.
Spokane then reeled off six unanswered goals, including five in the third period, to rout Prince George.