The 25-year-old Dons club captain has signed a new three-and-a-half-year deal that ties him to the club until the summer of 2013.
"Players of Dean Lewington's quality are absolutely integral in getting to where we want to be, so I'm over the moon that he's going to be part of what we're trying to achieve," manager Paul Ince told the Dons' official website.
"He was fantastic during my first spell with the Club, clearly capable of playing at a higher level, so I was actually surprised to still find him here when I came back!"
"But Lewie loves MK Dons, he loves the fans, he can see the giant strides we're taking to move forward and he wants to be part of that."
