He initially transferred to Texas A&M University in 1994, but failed the math portion of a junior-college exit exam and was ruled ineligible for the 1994 season.

In 2000, he was named to USA Today's All-Joe Team, recognizing the NFL's most "overlooked, ignored and hard-working" players.

[1] Williams intercepted his first career pass and returned it 20 yards for a touchdown, picking off Miami Dolphins quarterback A. J. Feeley on December 5, 2004, sealing the win for Buffalo 42-32 and breaking open a 3-point game with 1:55 left to play.

Following an advice by then defensive coordinator Mike Tomlin, Williams lost 15 pounds in the offseason.

On December 2, 2008, Pat and teammate Kevin Williams were suspended for 4 games by the league for violating its anti-doping policy, for use of a diuretic, which can be used as a masking agent for steroid use.

[6] On April 23, 2013, Pat Williams signed a one-day contract so that he could retire as a Minnesota Viking.

Pat Williams helped create a Lineman Academy located at the University of St. Thomas in St. Paul, Minnesota.