The 35-year-old is coming to the end of his testimonial season. Even though he will not receive a new deal, the club confirmed his testimonial match will still be going ahead with details set to be announced in the coming weeks.
He will be joined on his way out of the club by defender Keith Watson.
The former Dundee United man has been plagued with injuries since making the move to Perth in the summer of 2016.
Manager Tommy Wright said to the club’s website: “Chris is obviously the most notable of those being released as he has been here since the summer of 2008 and has made a huge contribution to the club’s success over the past decade, not least the Scottish Cup success in 2014, top-six league positions and European campaigns.
“Like Alan Mannus and Steven MacLean, Midgey has given me everything as a player and will always be well thought of and welcome back to McDiarmid Park.
“We’ve also decided not to renew the contract of Keith Watson, who has been so unlucky with injury in his two years here and that’s the main reason he hasn’t made the impact we all hoped, although I think anyone who saw him in his half-dozen starts would understand why we were keen to secure his services.”
St Johnstone have also confirmed that youth players Jamie Docherty, Daniel Jardine, Cameron Lumsden and Cammy Thomson will also be leaving the club when their current details expire at the end of the campaign.