Seth Tarver had 15 points to lead Oregon State past Southern Cal 49-44 on Saturday to sweep the season series.
Roeland Schaftenaar made four free throws in the final minute to seal the win for the Beavers (13-15, 7-10 Pac-10), who had lost two straight.
Mike Gerrity had 13 points and Dwight Lewis 11 for the Trojans (16-11, 8-7) during their final home game of the season.
The Trojans shot 29.4 percent from the field and committed 20 turnovers. It was their third straight loss.
Gerrity made a layup with 34 seconds left for the Trojans final basket, pulling the team as close as 46-44 with 33 seconds left.
The Beavers had 11 steals and scored 19 points off the Trojans' turnovers.
After trailing by one at halftime, Oregon State opened the second half with an 11-4 run to take control of the game.