MK Dons have released Sean O'Hanlon, Jude Stirling, Danny Woodards and Stuart Searle following their League One play-off exit to Peterborough.
O'Hanlon had been at the club for five years and made 180 appearances, while fellow defender Stirling joined the Dons in 2007.
Defender Woodards and goalkeeper Searle both joined the club in 2009.
Dons boss Karl Robinson told the club website: "Sean has been a phenomenal servant to this club."
He added: "Telling Sean he was a free agent is one of the hardest things I have ever had to do as manager."
The Dons are currently in contract discussions with young trio Tom Flanagan, Adam Chicksen and Charlie Collins.