"Northern Illinois has a great tradition, great football program," Williams said. "We sat down as a family and looked it up and felt it was a great fit for me."
Williams completed 96 of 179 passes for 1,725 yards, 18 touchdowns and six interceptions during his junior season.
Williams is Northern Illinois' first Class of 2012 recruit.
Scott Powers covers high school and college sports for ESPNChicago.com and can be reached at firstname.lastname@example.org.