Undrafted in 1990 after four years in college, Williams signed with the Chicago Bulls in 1990, playing four seasons with the team, mostly as a reserve, and winning three championship rings in his first three NBA seasons. On 7 June 1991, in game 3 of the finals against the Lakers, in Los Angeles, he scored four points (all from the free throw line), grabbed two rebounds and handed out two assists in only 11 minutes of play, in an eventual 104–96 overtime win.