DeCastro, 31, was released with a non-football injury designation. He was in the final year of his contract with a $14.2 million cap hit. Releasing him saves the Steelers $8.75 million in cap space.
DeCastro didn’t participate in minicamp recently, and the Steelers also brought in Pro Bowl guard Trai Turner for a visit last week.
DeCastro was the Steelers’ first-round pick (24th overall) in the 2012 draft.
“David was without a doubt one of the premier offensive linemen during his time with us,” Steelers general manager Kevin Colbert said in a statement. “He helped us win a lot of football games, but it was David’s consistency, reliability and professionalism that stood out more than anything else. We wish him the best moving forward in his career.”
DeCastro missed the first two games of 2020 with lingering knee issues but appeared in 13 of Pittsburgh’s final 14 games. When asked a week ago about DeCastro, coach Mike Tomlin said, “If I thought injury circumstances or reasons why people were not participating were significant, I would share them with you.”
With DeCastro’s release, the Steelers will have one returning starter on the offensive line: Chukwuma Okorafor, who is likely moving from last season’s spot on the right to left tackle. Kevin Dotson also started for DeCastro a few times last season, but he’s slated to be the left guard.
ESPN’s Brooke Pryor and The Associated Press contributed to this report.