Williams, 29, signed a four-year, $13.5 million contract with the Bills before the 2014 season. He started the first three games in '14 before being placed on injured reserve with a back injury.
The Bills will save $1.975 million off their 2015 cap and $1.925 million off their 2016 cap by releasing Williams. The team can carry over its unused 2015 cap space into the 2016 season, when the Bills have about $5 million in cap space, according to ESPN Stats & Information figures using a $150 million projected salary cap.
Williams waited to report to the Bills this offseason until the mandatory minicamp in June, making him the only Bills player not to report to the team during voluntary organized team activities. He sat out the three practices of minicamp as he continued to recover from a procedure on his back.
The Bills are expected to begin training camp this week with free-agent signing Richie Incognito at first-team left guard and third-round rookie John Miller at first-team right guard. Kraig Urbik and Cyril Richardson are the only other offensive linemen on the roster with NFL experience at guard.
Williams' release, coupled with veteran tackle Wayne Hunter asking for his release and retiring last week, means the Bills have two open spots on their 90-man roster.
The Chicago Bears selected Williams 14th overall in the 2008 draft.