The Cardinals (10-2), who had lost two of their previous three games, shot 46.3 percent (31 of 67) compared to 32 percent (16 of 50) for the Cougars.
Washington State (3-6), coming off a 62-55 upset win over No. 20 Ohio State on Dec. 15, posted its lowest point total of the season.
Tied at 11 after 11 minutes, Louisville closed out the half on a 24-3 run.
Bria Smith added 13 points, Shoni Schimmel 12 and Jude Schimmel 10 for the Cardinals, who were playing their first game without starting forward Shawnta' Dyer. The sophomore, who was averaging 7.5 points and 5.5 rebounds per game, tore her ACL and MCL in her left knee during practice Sunday and is out for the rest of the season.
Lia Galdeira's 13 points led Washington State.