Shaun Williams struck a superb equaliser as MK Dons earned a point at bottom-of-the-table Portsmouth, who are now without a win in 23 games.
David Connolly had put Pompey ahead when he glanced in Jed Wallace's free-kick for his first goal for the club.
But five minutes later, Williams fired in an unstoppable volley from Daniel Powell's cross to restore parity.
Dons forward Izale McLeod could have won it against his ex-club, but somehow failed to connect to Powell's cross.
The result continues financially-stricken Portsmouth's poor run of form, with their last win in any competitions coming in October against Shrewsbury at Fratton Park.