Williams announced his decision to hang it up on Friday. The 35-year-old was a fifth-round pick in the 2006 NFL Draft. The five-time Pro Bowl selection has played for the Bills for the entirety of his decorated tenure.
Williams has 48.5 sacks and 607 tackles in 182 appearances during his 13-year career in Buffalo.
"This isn't easy. It was never going to be," Williams wrote in a letter posted by the Bills. "There's no perfect time to retire from a game, a franchise, and a city that mean so much to me and my family. But it's time to hang up my cleats."
Williams went on to talk about the Buffalo community and raising his family in the area, before thanking those who helped him along the way.
"Thank you to the Pegulas, to the Wilson family, to my teammates, to Sean McDermott and Brandon Beane, to my family, and to the fans," Williams said. "I've been at this a really long time but it doesn't feel like it, and that's a testament to your unwavering support. I could not be more grateful to retire as a lifelong Buffalo Bill."
The 6-foot-1, 303-pound defensive lineman has 31 tackles, five sacks, a pass defensed, a forced fumble and a fumble recovery in 15 starts this season.