The seven-year pro had one year remaining on his contract, signed in 2014.
Shields, 29, suffered a concussion in Week 1. Coach Mike McCarthy said in his postseason news conference last month that Shields still had not cleared concussion protocol.
Despite suffering a fourth concussion in the NFL -- two in a nine-month span -- Shields said in January that he still hopes to play.
"I'm thinking it's not over. I've still got more (football) in me," Shields said, via the Wisconsin State Journal. "I understand why you ask (why I'd continue to play). I don't know. I just love the game, man, and I feel that I can get back out there and play."
Shields announced his release earlier Wednesday morning in an Instagram post.
Those are some interesting hashtags he's got going on.
If Shields decides to try continuing his career, he would have to clear concussion protocol during a physical with whatever team takes a gamble on the corner.
A Pro Bowler in 2014, Shields' injury at the start of this season discombobulated the Packers' secondary, leading to young players entering the lineup and defensive backs playing out of position. With Shields gone for good, general manager Ted Thompson will need to bolster the unit in 2017.