The victory improved the Cougars' overall record to 7-13 and Pac-10 mark to 3-9. The Huskies (13-10, 7-5) are in fourth place.
Last Thursday night, the Cougars lost to Washington, 79-65, at Seattle.
On Sunday, Wallace hit five of eight three-point shots in the first half as the Cougars led, 45-35, at halftime.
The Huskies trailed only 75-74 with 3:31 left after a three-point shot by Greg Hill. But the Cougars pulled away by hitting seven of eight free throws in the game's final two minutes.
Phil Zevenbergen and Hill led the Huskies with 23 points apiece. Chris Welp had 20 before fouling out with 5:02 left.
Oregon State 79, Chicago State 52--Jose Ortiz scored 22 points at Corvallis, Ore., as the Beavers pulled away in the second half to a nonconference victory.
Ortiz also contributed five steals and seven rebounds as the Beavers improved to 17-4 overall. Oregon State is tied with UCLA atop the Pac-10 at 9-3.
Freshman guard Gary Payton added 18 points and a game-high 8 assists as the Beavers won their sixth straight.
Chicago State, an independent, trailed only 25-24 at halftime. But 22 turnovers and 25 personal fouls were the difference as the Cougars (8-13) dropped their seventh straight.