USC fell to 48-9 in its all-time series with Oregon State.
The Beavers snapped an 11-match losing streak to USC and won for the first time since they took a five-set win over the Trojans in 2008. It was OSU's second win in 35 meetings with USC, dating back to 1996.
The Trojans are still in search of one more victory in order to become tournament eligible.
Junior OH Samantha Bricio recorded four service aces to give her 76 this season, and 204 in her career. It was the 28th time in her career that she has had at least three aces in a single match.
Bricio finished with 22 kills and 15 digs for her 14th double-double this season (36th of her career).
Sophomore libero Taylor Whittingham had her 22nd match in double digits for digs and finished with 20. It was her 10th match with 20 digs or more this year.