The Seahawks gained 146 yards on returns of four interceptions off Philadelphia quarterback Vince Young.
Hawthorne produced the backbreaking play, picking off a pass on 1st-and-10 after Young had driven the Eagles to the Seattle 22. A Philadelphia touchdown would have brought the Eagles within three points, but Hawthorne's interception clinched Seattle's third win in four games.
Marshawn Lynch ran for 148 yards and two touchdowns that gave the Seahawks a 14-0 lead. Tarvaris Jackson completed 13-of-16 passes for 190 yards and threw an 11-yard scoring pass to Golden Tate in the third period.
Seattle improved to 5-7 and stayed mathematically alive in the race for the NFC West title. San Francisco, however, can clinch the division title Sunday with a victory at home against St. Louis.
The Eagles, again without quarterback Michael Vick due to his injured ribs, fell to 4-7.
Lynch, who coming into the game was 17th in the NFL with 70.6 rushing yards per game, ran 15 yards for a score in the first period and dashed 40 yards for another touchdown in the second to end an 88-yard drive.