Carr completed 11 of his 13 passes for 143 yards and Matt McGloin went 10- of-19 for 105 yards with a touchdown and an interception for the Raiders.
Denarius Moore caught two touchdowns on three receptions for 58 yards, while Mychal Rivera and Brice Butler both also hauled in TD passes. Latavius Murray added a rushing score and rookie George Atkinson rushed for 63 yards on eight carries.
Terrelle Pryor threw for 134 yards and a touchdown on 11-of-17 efficiency and B.J. Daniels also completed a TD pass for Seattle. Starter Russell Wilson completed all three of his passes on the opening drive for 77 yards and a score.
Bryan Walters, Phil Bates and Luke Wilson each caught touchdown passes in defeat.
The Seahawks trailed 35-21 at half, but got within a score after Walters' TD catch from Daniels made it a 38-31 game with 4:30 to play. Giorgio Tavecchio split the uprights from 47 yards out with less than two minutes left that sealed the win.
Oakland will open its season on the road against the New York Jets on Sept. 7, while Seattle will begin defense of its title at home against Green Bay on Sept. 4.