Mitchel-King was brought to Kingsmeadow by manager Terry Brown from Crewe but his debut was delayed until December due to a spate of injuries.
However, Mitchel-King is now a regular in the Dons' back four and looking to help them push back up the League Two table.
He said: "I was frustrated that I was not contributing, especially after Terry showed faith by signing me.
"I didn't really feel part of the team until I got into the side, but I hope I can now look people in the eye.
"This club has a special history and fanbase and I want to be part of taking it to the next level."
