The 30-year-old Willson has played sparingly this season as the Seahawks' No. 4 tight end behind Greg Olsen, Will Dissly and Jacob Hollister. They just activated rookie fourth-round pick Colby Parkinson from the non-football injury list, adding to their logjam at the position.
Seattle also has undrafted rookie Tyler Mabry on its practice squad as well as rookie seventh-round pick Stephen Sullivan, who plays tight end and defensive end. Sullivan made his NFL debut at defensive end Sunday after being elevated for the Seahawks' win over the San Francisco 49ers.
Willson has played 10 offensive snaps in five games without a target.
Willson was a fifth-round pick by the Seahawks in 2013, the year they won Super Bowl XLVIII. He spent his first five seasons with Seattle and played for the Detroit Lions in 2018 before returning to the Seahawks the following year.
Releasing Willson will leave the Seahawks with two open spots on their 53-man roster, which figure to be filled by defensive ends Carlos Dunlap and Rasheem Green. The Seahawks currently have a roster exemption for Dunlap after acquiring him in a trade last week with the Cincinnati Bengals. Coach Pete Carroll has said he expects Green to return this week off injured reserve.
In other Seahawks news, wide receiver Phillip Dorsett had surgery Tuesday to repair the foot injury that's sidelined him all season. A source told ESPN that part of the issue with Dorsett's foot was bone spurs that needed to be cleaned out. He had been able to run but wasn't 100%. There's some hope that Dorsett can return later this season, the source said, but it's not a sure thing.
Dorsett has been on injured reserve since late September and has been eligible to return. Asked about Dorsett's status on Monday, coach Pete Carroll made it clear he wasn't coming back anytime soon.
"Phillip Dorsett is not doing well," he said. "His foot has really not responded. We'll let you know. We haven't done anything about that yet but he's not ready to go."
Asked if surgery was a possibility, Carroll said: "It's not ready to be disclosed yet to tell you what's going on, but it's not looking good for the near future, and he's been doing everything he can and is frustrated and all that. So in the next couple days, we'll get a little more clarity on it."
The Seahawks signed the former first-round pick to a one-year, minimum-salary deal in March. Their offense has been leading the NFL in scoring, with Tyler Lockett and DK Metcalf tied for the league lead in touchdown receptions at seven apiece. David Moore, rookie Freddie Swain and Penny Hart are the other wide receivers on Seattle's 53-man roster. Josh Gordon remains on the reserve/suspended list as he awaits reinstatement by the NFL from his indefinite suspension.
Also Tuesday, the Seahawks waived linebackers Mychal Kendricks and Michael Divinity off their practice squad. One of those open spots on the practice squad could go to running back Alex Collins, who began COVID-19 testing Friday.