He was selected by the Ravens in the third round of the 2013 NFL draft He played college football for the Missouri Southern Lions.

Williams played college football for the Missouri Southern Lions and was later selected in the third round of the 2013 NFL draft by the Baltimore Ravens, spending his first 8 seasons with the team before joining the Kansas City Chiefs in his last season, in march 9 2017, Williams signed a five-year $54 million contract extension with the Baltimore Ravens where he recorded a three career high tackles.

On November 30, 2022, Brandon Williams signed with the Kansas City Chiefs practice squad and was later promoted to the active roster on December 8, where he won Super Bowl LVII against the Philadelphia Eagles, and was later released from the team before retiring on November 5, 2024.

He was a major contributor as a freshman finishing eighth on the team in tackles with 38, including three for loss and 1.5 sacks.

After a medical redshirt in 2009 due to a back injury,[1] he returned the following year in 2010 and led the Lions with nine sacks and 17.5 tackles for loss and was named to three-different All-American teams.

[5] Williams became the first Missouri Southern State player to be drafted since Allen Barbre was selected by the Green Bay Packers in 2007.

Williams made his NFL debut on September 29, 2013, recording a fumble recovery and logging 20 snaps against the Buffalo Bills.

Williams made his first-career start against the Cincinnati Bengals in the 2014 season opener, recording two tackles.

In Week 7, Williams recorded his fourth sack and blocked a field goal against the New York Jets.