Arizona (18-9, 7-2) won its fourth straight game and remained deadlocked at the top with UCLA and Stanford. Both won Saturday.
Felicia Ragland scored 14 points and Ericka Cook added 11 for the Beavers (9-12, 5-4), who lost to Arizona for the sixth straight time.
Arizona led 9-2 after the first four minutes and never let the Beavers get closer than three points thereafter. The Wildcats led 39-27 at halftime and scored the first 11 points of the second half to go up by 23.
Oregon State cut the lead to 63-49 with 1:03 left, but didn't score again.
The Beavers shot just 21 percent and were outrebounded 48-38.