[3] Williams then lived in Daytona Beach, Florida, and attended Mainland High School there, where he was a two-sport athlete in football and track.

[7] As a senior, he had 103 tackles and 10.5 sacks, helping Mainland to reach the FHSAA 6A state semi-finals, where they lost to Miami Central 7–17.

However, the loss was overturned in August 2012 as Miami Central forfeited its entire season due to a transfer infraction.

[12] After recording 74 tackles and six sacks, Williams was a named a first-team All-Pac-12 Conference selection and was an All-American by ESPN.

He was named Team MVP, first-team All-Pac-12 and was an All-American by the American Football Coaches Association (AFCA) and ESPN.

[15][16] After his junior season, Williams announced that he would forgo his senior year and enter the 2015 NFL draft.

[36] Opening the season against the Cincinnati Bengals on September 11, 2016, Williams had 2.5 sacks for his first career multi-sack game.

[37] He had a total of 7 sacks on the season, and as recognition for his great play, he was selected as a first-team alternate for the 2017 Pro Bowl.

[41] During Week 16 against the Green Bay Packers, he was disqualified for the first time in his NFL career after throwing a punch on Bryan Bulaga.

[47] He finished the 2019 season with a half-sack, 46 total tackles (21 solo), three passes defended, and one forced fumble in 15 games and 12 starts.

[52] In Week 1 against the Pittsburgh Steelers on Monday Night Football, Williams recorded his first sack of the season on Ben Roethlisberger during the 26–16 loss.

[69] On October 30, 2023, Williams was traded to the Seattle Seahawks in exchange for a second-round pick in the 2024 NFL draft (No.

[74] On December 1, 2024, Williams scored his first NFL touchdown on a 92-yard interception return in the second quarter off Aaron Rodgers during a Week 13 game against his former team, the New York Jets.

[75] At 310 lbs, the return for a touchdown gave him the NFL record for the heaviest player ever to do so as the former Jet and former Giant secured a signature career moment at MetLife Stadium.