In a statement posted Wednesday on Twitter, the 31-year-old Willson wrote that he spent days in the hospital during this offseason with a severe pericardial effusion, which is a buildup of extra fluid in the space around the heart.
"That situation has really challenged me as an individual and changed my perspective on a lot of things with regards to my life," Willson wrote. "After reflecting on everything yesterday and being in the building, I have decided that it's time for me to begin with the next chapter of my life."
The Seahawks released Willson on Wednesday, leaving them with an opening on their 80-man roster.
They had brought him back for a fourth stint with the team on Tuesday. That was to reinforce their depth as Colby Parkinson deals with a foot injury that may keep him sidelined past their Sept. 12 opener against the Indianapolis Colts.
Willson was a member of the 2013 Seahawks team that won Super Bowl XLVIII, having been drafted in the fifth round that year out of Rice, as well as the 2014 club that came a yard short of repeating in Super Bowl XLIX. He spent his first five seasons with Seattle and returned in 2019 after a year with the Detroit Lions and an offseason stint with the Raiders. He spent time with the Seahawks and Baltimore Ravens last year.
In 102 career games, Willson has 111 catches for 1,307 yards and 11 touchdowns. That doesn't include his most famous play, a 2-point conversion that will live on in Seahawks lore. Willson caught a desperation heave from Russell Wilson late in the fourth quarter of the 2014 NFC Championship Game, part of the Seahawks' unlikely comeback against the Green Bay Packers.
Willson's energy and jocular personality made him a fan favorite and a popular player in Seattle's locker room. He was the progenitor of the club's Techno Thursday movement in 2017, which featured players dancing on the practice field as techno music blared through the loudspeakers.
"Certain people just have more juice than others," coach Pete Carroll said Tuesday after Willson took part in practice. "Luke has always been a great part of that for us and just one of my favorites that we've had in the program over the years."
In his statement, Willson thanked the Seahawks, their fans, his hometown of LaSalle, Ontario, and the coaches and teachers who have helped him along the way.
"I have always tried my best to be a true representation of the characteristics that make up our area," he wrote. "I hope I've made you proud.
"Football is really all I know. It's all I've done for the last 2 decades. I'll be honest, I have no idea what's next at the moment. But whatever it is, you can be sure that I will bring a lot of energy to it."