[1] Williamson was signed by the Houston Oilers of the National Football League in June 1993.
[5][4][6] Williamson later re-signed with the Oilers on November 21, 1994, and was on the active roster for the final six games of the regular season.
[7][5] Williamson signed with the Anaheim Piranhas of the Arena Football League (AFL) in December 1996.
[9] However, Williamson left the team after Ron Lopez was named the starting quarterback before the first game of the 1997 AFL season.
[9] Williamson later returned to the Piranhas and played in two games for them that year, completing six of 14 passes (42.9%) for 73 yards, one touchdown, and one interception.