In March 2012, Williams was suspended from the NFL as a result of his admitted involvement in the New Orleans Saints bounty scandal, under which bounties were paid for causing injuries that would take targeted players on opponent teams out of games. Williams' suspension was lifted a year later, and he returned to the NFL.
Gregg Williams was a head coach for the Class 5 Belton High School Pirate football team in Belton, Missouri. He attended Northeast Missouri State University (now Truman State University) in Kirksville, Missouri. Williams was an assistant coach for the University of Houston under former Redskins head coach, Jack Pardee.
In 1990 Williams became the Special Teams coach of the Houston Oilers under then defensive coordinator, Buddy Ryan. From 1994–1996, Williams was the linebackers coach for the Oilers. From 1997–2000, Williams was promoted to defensive coordinator of the now Tennessee Titans after the Oilers moved out of Houston. As the defensive coordinator, the Titans led the league in total defense and only gave up 191 points, the third fewest in the NFL since the league adopted the 16-game schedule in 1978. The defense also helped lead the Titans to Super Bowl XXXIV where they lost to the St. Louis Rams.
Williams joined the Buffalo Bills as head coach in 2001 along with new team President and general manager Tom Donahoe. After three seasons in which the team compiled records of 3–13, 8–8, and 6–10 under his leadership, Williams' contract was not renewed after the 2003 season. It is the only head coaching position Williams has held in the NFL.
After his release from Buffalo, Williams was at the top of several NFL teams' list for the position of defensive coordinator. Williams quickly signed with the Washington Redskins, the only team with which he interviewed, because Head Coach Joe Gibbs offered him total autonomy over his defensive players and defensive coaching staff.
In Washington, with Williams' aggressive defensive scheme, the Redskins' defense ranked third in the NFL in 2004 and ninth in 2005.
On January 3, 2006, Williams signed a three-year extension to remain with the Redskins, which made him the highest paid assistant coach in the NFL.
His defense struggled in 2006, at point ranked 30th in the League. However, the 2007 season was a vast improvement for Williams. The defense ranked within the top ten in the NFC, and the team finished 9–7, with a loss in the wildcard round to the Seattle Seahawks. Williams had established a particularly close relationship with 24-year-old free safety Sean Taylor, calling him "the best player [he'd] ever coached." When Taylor was murdered mid-season on November 27, 2007, Williams was deeply affected. In tribute to Taylor, Williams called a defensive play with only ten men for the first play of the Redskins' first game after the tragedy, a November 30, 2007 game against the Buffalo Bills. For the remainder of the season, Williams ran an inspired defense which performed, along with the rest of the team, to honor Taylor's memory, highlighted by holding star running back Adrian Peterson of the Minnesota Vikings to 27 yards on December 23, 2007, and allowing a franchise-low one yard rushing to the Dallas Cowboys on December 30, 2007, sealing a playoff seed. After Joe Gibbs retired, Williams was considered to be the most popular candidate to take over as Head Coach of the Washington Redskins. He interviewed four times with team owner Daniel Snyder. However, on January 26, 2008, Williams was fired, along with offensive coordinator Al Saunders, with Jim Zorn ultimately getting the job.
On February 6, 2008, Williams became the defensive coordinator of the Jacksonville Jaguars. The position was vacated by Mike Smith who was hired to coach the Atlanta Falcons.
Williams was hired by the New Orleans Saints on January 15, 2009. Head coach Sean Payton, who was heavily involved in the effort to recruit Williams to the team, raved about Williams "because he was so impressive and prepared" in his interview. In fact, Williams was so impressive that Payton offered and took a voluntary $250,000 cut in salary to help facilitate his signing with the team. He took over a Saints defense ranked 23rd in the NFL in yards allowed and tied for 26th in points allowed in 2008. Williams' approach yielded immediate results, as the 2009 Saints recorded 35 defensive takeaways, second in the league, and the aggressive defense played an integral role in the Saints' run to their first Super Bowl championship.
However, in the 2010 and 2011 seasons, the defense (although showing statistical improvement in some other categories) failed to repeat its turnover successes. The Saints were knocked out of the 2011 playoffs in a 36–32 loss to San Francisco, in which the defense played well for most of the game but twice failed to hold a Saints lead during the last four minutes. At that time, the relationship between Williams and Payton deteriorated, with Payton regarding Williams as a "rogue coach". William's departure from the Saints was originally publicized not as a dismissal since his contract was expiring, however Loomis and Payton fired Williams telling him "There's no place for this in this organization or this league" after the NFL informed the Saints that it had reopened its investigation in the illegal bounty fund. It was widely reported that Williams would leave the Saints to become defensive coordinator of the St. Louis Rams, under their new head coach Jeff Fisher, for whom Williams had also worked when Fisher was the head coach at Tennessee.
On February 3, 2012, Williams was formally introduced as the Rams' new defensive coordinator. A little over a month later, on March 21, Williams would be suspended indefinitely for his role in the Saints bounty scandal and be subsequently released on January 2, 2013 before ever working a day for the Rams.
After the NFL reinstated Williams, it was announced of February 7, 2013 that the Titans hired him as a senior assistant coach for its defense.
Williams was renamed defensive coordinator for the Rams on February 12, 2014.
On December 12, 2016, the Los Angeles Rams fired head coach Jeff Fisher. His coaching staff, along with Williams, was released at the end of the season.
Williams was hired as the defensive coordinator of the Cleveland Browns on January, 7, 2017.
On March 2, 2012, it was revealed that during Williams' tenure the Saints ran an illegal "bounty fund" which paid players for causing injuries to opponents that would result in those players leaving the game. The NFL found that Williams and as many as 27 Saints defensive players were involved in the scheme. An unidentified Saints player first alerted the NFL to the scheme in the 2010 offseason, but the investigation stalled until the NFL found irrefutable evidence of a bounty system just before the 2011–12 playoffs.
A league investigation revealed that Williams began the bounty system soon after he arrived in New Orleans, after Payton charged him to make the Saints' defense "nasty." Players usually earned $1,000 for "cart-offs" and $1,500 for "knockouts" during the regular season (though payments were known to triple during the playoffs), though they were encouraged to put their winnings back into the pot in order to raise the stakes as the season went on. The investigation also found that Payton tried to cover up the scheme, and that linebackers coach Joe Vitt, whom Payton had assigned to monitor Williams (the two reportedly didn't get along), knew about the broad lines of the scheme and did nothing.
Soon after the investigation came to light, several former players and coaches with the Bills and Redskins claimed that Williams operated similar systems while he was with them. Former NFL coach and current NBC Sports analyst Tony Dungy said that he was certain Williams operated a similar system with the Oilers/Titans as well. However, several players, coaches and team executives who were with Williams in Houston/Tennessee, Buffalo and Washington have denied that Williams ever ran a bounty system.
Williams was summoned to NFL headquarters after the investigation concluded in mid-February. He initially denied any involvement, but recanted and admitted everything in a meeting with NFL Commissioner Roger Goodell. He issued a statement apologizing for his role, saying that he'd known it was wrong from the start. On March 21, 2012, the NFL suspended Williams indefinitely for "conduct detrimental" to the league, effective that day. In a statement, the NFL said that its investigation had found that Williams not only administered the bounty program and occasionally contributed some of his own money to the bounty pool, but lied to league investigators about his role. Consequently, the suspension would run until the end of the 2012 season at the earliest. When Williams applied for reinstatement, Goodell considered how much Williams cooperated with the NFL in its continuing investigation; Goodell also expected Williams to participate in league efforts to eliminate bounty systems altogether. The NFL is still investigating allegations that Williams ran a bounty program in Washington.
Williams apologized again after he learned of his punishment, and said he hoped to return to coaching in the future. However, Fisher said that neither he nor the Rams knew about the bounty program, and he would have not have hired Williams had he known that Williams might be facing a year's suspension.
On April 5, documentary filmmaker Sean Pamphilon released audio of a meeting Williams held with his defense before their 2012 divisional playoff game against the San Francisco 49ers. In a profanity-laced speech, Williams instructed his defense to target several 49ers players. He ordered his men to try to knock out running back Kendall Hunter, even if it meant hitting him out of bounds. He specifically directed them to try to tear wide receiver Michael Crabtree's ACL, and to go after wide receiver Kyle Williams specifically because he had a history of concussions. Pamphilon, who was doing a documentary on the media's effect on football from Pee-Wee all the way to the NFL, released the audio to Yahoo! Sports because he was sickened by what he heard.
On December 12, the Associated Press reported that, according to a transcript of the bounty appeal hearing, Williams had testified that he had wanted to shut down the system after the league began investigating, but was overruled by Saints linebackers coach Joe Vitt. Vitt, however, denied the claims.
On February 7, 2013, Williams was reinstated by the NFL and officially hired by the Tennessee Titans as a senior assistant defensive coach. In the official statement released by the league, commissioner Roger Goodell cited Williams' acceptance of responsibility for his role in the bounty program and pledge to never be involved in another such "pay for performance" system as the main reasons for Williams' reinstatement after just one year.