Cooper was the most high-profile name to be released as the 49ers trimmed their roster to the league-mandated 53 players.
A No. 7 overall pick of the Arizona Cardinals in the 2013 NFL Draft out of North Carolina, Cooper never displayed the talent expected of a top-10 selection.
The 28-year-old Cooper signed a one-year deal with San Francisco in March, his fourth team in five years. He was expected to compete for a starting job on the offensive line.
The 6-foot-2, 308-pound Cooper spent last season with the Dallas Cowboys, starting the final 13 games after he was inactive for the first three. However, he suffered a knee injury in the regular-season finale and subsequently underwent surgery.
As a rookie, Cooper started two games in 2014 and then appeared in 14 games with the Cardinals the following season, making nine starts.
Cooper was acquired by the New England Patriots in March 2016 and waived by the club in October of that year.
The Cleveland Browns claimed Cooper off waivers and he appeared in five games with them, making three starts, before he was waived in December 2016.