Washington has won two of three games, bouncing back after dropping nine straight. Stewart finished with 14 points and 12 rebounds.
Tonight’s game will be televised on ESPN2, and the Huskies will need to find a way to get back on track during the last week of the regular season.
The Cougars (15-14, 6-10 Pac-12) swept the season series for the first time since the 2016-17 season.
Washington forced 17 turnovers, and held Cal to 11 field goals and 24 percent shooting in a game that showed the team's athletic promise.
This was UCLA's first regular season sweep of Washington since the 2016-17 season.