Carl Baker will join Portsmouth upon the expiry of his contract.
He has signed a two-year deal at Fratton Park and the move will become official from 1st July.
Manager Karl Robinson told mkdons.com: “We’re disappointed Carl will not be with us next season but we understand his excitement at this new challenge.
“He has been a terrific servant to this Football Club and he played a pivotal role in our promotion to the Championship. I’m sure if he’d have remained fit last season, we’d have had a much better chance of remaining in the division.
“On behalf of the Club, I’d like to thank Carl for his commitment and contribution and wish him all the best with his new club.”
Baker departs Stadium MK having scored 15 goals in 72 appearances for the Dons.
He joined the Club on a free transfer in September 2014 and made his debut in the 2-0 victory over Yeovil Town at Huish Park.
Baker scored 10 goals in 35 appearances in total during the 2014/15 campaign, helping the men from MK1 to their first-ever promotion to the Championship. His performances saw him earn the Player of the Year accolade, as voted for by the supporters.
The winger started last season in good form and found the net four times in the first nine matches but an injury in early January ruled him out until March. He finished the season with five goals and 37 games to his name.
Meanwhile, Alex Revell has agreed to join Northampton Town on 1st July, following the expiry of his contract with MK Dons.
The striker moved to Stadium MK on a short-term deal in February and scored four goals in 17 appearances at the back end of last season. He will be fondly remembered for saving a penalty in the 1-1 draw with Preston North End at Deepdale.
The Club would like to thank both Carl and Alex for their contributions and wish them every success in the future.