Campbell passed for 310 yards, completing 15-of-27 through the air, with five receptions going to Darrius Heyward-Bey for 105 yards and a score.
Darren McFadden racked up for 111 yards on 21 carries and caught two passes for 24 yards for the Raiders (4-4), who posted their second straight win.
Seattle quarterback Matt Hasselbeck completed 13 of 32 pass attempts for 160 yards and an interception for Seattle (4-3).
Hasselbeck was harassed all day by the Raiders' defense, which sacked him seven times in the one-sided loss.
Notable deaths of 2014 [PHOTOS]