Williams led Peoria Manual to the final two of four consecutive IHSA class AA boys state basketball tournaments, in 1996 as a sophomore and again in 1997 as a junior.

After high school, Williams attended the University of Illinois, and played three seasons for the Fighting Illini under head coach Bill Self, leading the team to a string of NCAA Tournament appearances.

Unfortunately, new GM Isiah Thomas then traded for star point guard Stephon Marbury, and Williams was relegated back to the end of the bench.

The Chicago Bulls acquired him as part of a multi-player trade in the next off-season, where Williams was popular due to his time with the Illini, and expected him to compete with Kirk Hinrich for the starting point guard job, but he showed up to training camp out of shape and spent most of the 2004–05 season on injured reserve.

On June 10, 2009, Williams and his younger brother, Aaron, were arrested on drug charges at his Peoria, Illinois home after agents seized 55 grams of marijuana.