Williams attended Southern University, the same school his brother Achilles attended. At Southern, Williams concentrated on his academics, not playing football until his senior year, as a graduate student. That year, he tied the NCAA Division I-AA record for most interceptions.
Despite playing only one year in college, Williams' numbers impressed the then-Phoenix Cardinals enough that they selected him in the third round of the 1991 NFL Draft, Williams quickly established himself with an exceptional rookie season, tying the NFL lead for interceptions. By 1997, Williams had already notched four Pro Bowl appearances and had established himself as the Cardinals' top cornerback, routinely covering the opponents' lead receivers. In the 1998 season, Williams helped the Cardinals win their first playoff game since 1947 by intercepting two passes from Troy Aikman in a 20-7 win over the Dallas Cowboys, and added another interception in the Cardinals 41-21 loss in the divisional round. Despite playing mostly for bad teams for most of his 11 years with the Cardinals (1998 was the only time he played on a winning team during his stay in Arizona), Williams was recognized as one of the best cornerbacks in the league, making six Pro Bowls in all as a Cardinal. He is regarded as one of the best defenders and players in Cardinals history, as well as one of the greatest shutdown corners of all time. In 2000, he tied an NFL record by returning a fumble (caused by Mark Maddox) 104 yards for a touchdown in a game against the Washington Redskins.
In Week 3 of the 1999 season, Williams delivered the hit which ultimately ended Hall of Fame San Francisco 49ers' quarterback Steve Young's career. Williams came in on a cornerback blitz from Young's blindside and scored a violent, but clean, hit on Young. Running backLawrence Phillips was supposed to block Williams, but missed. This occurred on national television, a Monday Night Football game, and left Young unconscious on the field for several minutes. Young suffered a severe concussion that effectively ended his career; he didn't play again for the rest of the season, after which the 49ers all but forced him to retire.
In 2001, Williams was traded to the St. Louis Rams on draft day in exchange for picks in the second and fourth rounds. Due to roster concerns, Williams switched to free safety. As one of the leaders of a much-improved defense, Williams got a chance to play in a play in the postseason for only the second time in his career. In the Rams divisional playoff game against the Green Bay Packers prior to the Super Bowl, Williams returned two interceptions from Packers quarterback Brett Favre for touchdowns and recovered a fumble. Then in the NFC title game, he intercepted a pass from Philadelphia Eagles quarterback Donovan McNabb, with 2 minutes left in regulation, clinching the game and ensuring the Rams' berth in Super Bowl XXXVI. However, the Rams lost that game to the New England Patriots.
After a lackluster season, in which he ended on the injured reserve list, Williams quietly retired during the 2005 offseason. Over his career he accumulated a staggering 12 defensive touchdowns (9 interceptions returned for a touchdown, and 3 fumbles recovered for touchdowns), and 55 career interceptions, cementing his place as one of the most dominating defensive backs of his era. He also recovered 23 fumbles and gained 1,075 total defensive return yards (807 from interceptions and 268 from fumbles). He was also a 4-time All-Pro selection. His 268 fumble return yards are an NFL record.
Williams was inducted into the Arizona Cardinals' Ring of Honor during the 2008-2009 football season during halftime of the Monday Night Football game against the San Francisco 49ers November 10, 2008.
On January 18, 2009, Williams was chosen to present the George Halas Trophy to the Arizona Cardinals after their victory in the NFC Championship game, resulting in the Cardinals first trip to the Super Bowl.
Williams is currently the founding pastor of Spirit of the Lord Family Church in St. Louis.
Williams made his final appearance in a football videogame in NFL Street 2. Williams and his wife, Tracy, have daughters Saenea (Aeneas spelled backward ), 11; Tirzah, 9; Cheyenne, 3 and a son : Lazarus, 6.