The move comes on the heels of a disappointing performance by the Bills backups in a 38-7 preseason loss to the Pittsburgh Steelers.
By acquiring Jackson, the Bills are placing more competition into the role of backup quarterback. Vince Young was the #2 QB in Saturday night's loss and finished 12 of 26 passing for 103 yards and two interceptions.
It was reported last weekend that the Seahawks are interested in a fifth round pick or better for Jackson. With the signing of Matt Flynn and the emergence of Russel Wilson this preseason, Jackson has become expendable in Seattle.
Jackson's last game against the Buffalo Bills was on December 5, 2010 when Jackson was a member of the Minnesota Vikings. In that game, Jackson completed 15 of 22 passes for 187 yards, two touchdowns, and three interceptions in a 38-14 Vikings win.
For his career, Jackson is 17-17 as a starter. The Seahawks signed him in free agency in July 2011. Jackson went 7-7 as a starter last year.