Matt Hasselbeck guided the Seahawks on a lengthy drive in which he completed five passes and Lynch's touchdown gave Seattle (3-2) a 10-point lead with less than seven minutes to go.
The Bears (4-2) pulled to within three after Devin Hester returned a punt 89 yards for a touchdown with 1:54 remaining, but could come no closer.
Hasselbeck threw for 242 yards and one touchdown on 25-of-40 passing and Justin Forsett gained 67 yards and rushed for a score on 10 carries.
Lynch ended the game with 44 yards on 17 carries.
Chicago got 290 yards on 17-of-39 passing from Jay Cutler.