Talia Walton had 15 points and 10 rebounds and Kristi Kingma had 14 points and eight rebounds for the Huskies (11-5, 3-2 Pac-12), who never trailed in the game.
Lia Galdeira led Washington State (5-11, 1-4) with 14 points, 12 rebounds and four steals before fouling out in the final minute.
Washington shot 40 percent in the first half and built a 36-21 lead. The Huskies struggled in the second half, making just 4 of 21 shots for 17 percent, to finish the game at 30 percent.
The Cougars weren't able to get closer than within four points in the second half.