Bell finished 27-of-37 for 413 yards for the Sooners (3-0) and finished without an interception.
Sterling Shepard caught eight passes for 123 yards and two Oklahoma touchdowns.
Roy Finch carried the ball six times for 68 yards to lead Oklahoma's 194-yard ground game. The Sooners churned up more than 300 yards rushing in both of their first two games.
Cody Green completed 17-of-23 passes for 226 yards for Tulsa (1-2). Tulsa had 95 total yards on the ground. They trailed 27-7 at halftime.