Mannion completed 24 of his 34 passes for 325 yards in guiding the Beavers to the second-most points in school history. The OSU record is 66, set against Washington State in 2008.
Markus Wheaton caught seven of Mannion's passes for 99 yards and Connor Hamlett totaled 80 yards and a touchdown on six receptions.
Terron Ward picked up 128 of the Beavers' rushing yards on 14 carries and scored twice.
Oregon State (8-2, 6-2 Pac-12) finished with 559 yards of total offense.
The Beavers' defense forced four California turnovers and held the Golden Bears' Allan Bridgford to 132 passing yards and intercepted him once.
California (3-9, 2-7) finished its season with five straight losses.