The 29-year-old did not play in 2020 after a torn labrum in his shoulder last September landed him on injured reserve. He posted 651 receiving yards and six touchdowns on 42 catches over 14 games in 2019.
Williams is now an unrestricted free agent in a class boasting with talent.
The wideout has already collected the guaranteed $22 million on his contract and will not count against next season's salary cap. Instead, the Raiders will avoid a cap hit of $11.6 million this year and $11.5 million next year.
Before Williams' release, Las Vegas was expected to begin the offseason $9.8 million over the cap, though the limit for 2021 has not been announced.
The Raiders posted the seventh-best passing offense last year (263.6 yards per game) despite Williams being unavailable. Tight end Darren Waller led all receivers with 107 catches for 1,196 yards and nine touchdowns while wideout Nelson Agholor added another 896 yards and eight touchdowns himself.
Rookie receiver Henry Ruggs III put up a modest showing in his debut season with 452 yards on 26 catches with two touchdowns, but was able to flash the potential that made him the No. 12 overall pick during last year's draft.
Cutting Williams made sense given his salary and the offenses' production without him.
Now he joins an unrestricted free agent wideout market that features A.J. Green, Allen Robinson, T.Y. Hilton and Sammy Watkins.