Williams announced his retirement from the NFL on Wednesday, Brooke Pryor of ESPN.com reports.
The 31-year-old was released by the Steelers in March, but he re-signed with the team a month later. Williams spent his entire eight-year career in Pittsburgh since after the Steelers selected him in the sixth round of the 2013 draft. Over 121 career regular-season games, he accumulated 479 total tackles and 20.5 sacks. With Williams out of the picture, Robert Spillane could take on a starting role alongside Devin Bush (knee) at inside linebacker.