NFL Network was first to report the release.
The move was expected for weeks. Clemons, 32, had 4½ sacks last season coming off surgery to repair a torn ACL. It was a significant drop in production from the previous three seasons, when he had at least 11 sacks each year after being traded to Seattle by the Eagles in 2010.
Clemons' release could mean the Seahawks believe they have a chance of signing one of the defensive linemen they are talking to this week.
Former Dallas Cowboys defensive lineman Jason Hatcher is in Seattle on Wednesday. The Seahawks also plan to talk to former Minnesota Vikings defensive end Jared Allen and had made calls to the agent of DeMarcus Ware, who was released by the Cowboys on Tuesday.
A source told ESPN NFL Insider Adam Schefter on Wednesday that Ware has agreed to a three-year, $30 million contract with the Broncos that includes $20 million in guarantees.