Wilcox, who had been in single digits three of the last four games, moved in front of Jon Brockman for second on the Huskies' all-time career points list with 1,814.
The victory also snapped a two-game overall losing streak for Washington (15-13, 7-8 Pac-12), which was coming off a 78-71 loss at Oregon on Wednesday. It was the Huskies' final regular-season road game. They finished the year 2-7 away from Seattle in Pac-12 play.
The loss snapped a four-game winning streak at Gill Coliseum for the Beavers (14-12, 6-8), who were coming off a 76-75 overtime victory over Washington State on Thursday night.
Roberto Nelson, who led the Pac-12 with an average of 21 points per game, had 17 points to lead the Beavers. Oregon State trailed by as many as 25 points.
The Huskies downed the Beavers 87-81 in Seattle in late January. In that game, freshman guard Nigel Williams-Goss had 32 points, an all-time high for a Washington freshman. He had added 14 points and 10 assists on Saturday against Oregon State.
Angus Brandt hit a 3-pointer to put the Beavers up 17-13 midway through the first half, before Olaf Schaftenaar hit another to keep the Huskies at bay, 20-17. Nelson made consecutive layups and a free throw to put Oregon State up 25-19.
Wilcox answered for the Huskies with a long jumper, a 3-pointer and a layup to spark an 11-0 run that was capped when Andrew Andrews' jumper made it a 30-25 UW lead.
The momentum stayed with Washington through the rest of the game and Wilcox pushed the margin to 42-31 with a late layup. The Huskies led 44-33 at the break.
Wilcox made a jumper that put the Huskies up 55-39 early in the second half and the game began to slip away for the Beavers. His alley-oop dunk pushed the lead to 59-40.
The Beavers rallied with a 9-2 run that narrowed the gap to 61-49. But Wilcox, with 14 points in the second half, consecutively hit a 3-pointer, a jumper and a dunk to put the Huskies up 80-55.