In-form striker Izale McLeod took his personal tally to three goals in two matches with a double strike as Danny Wilson's side destroyed already doomed Peterborough.
Nick Rizzo started the slaughter when firing the Dons ahead after only nine minutes.
The Australian midfielder seized on a sloppy clearance from Posh defender Mark Arber and arrowed his second goal of the season past motionless keeper Mark Tyler from fully 20 yards.
And they soon doubled their lead thanks to a perfectly-executed set-piece routine. Ex-Derby hitman McLeod was allowed to ghost into acres of space at the back post to bundle Gary Smith's delivery past the despairing dive of Tyler.
Former Posh forward Clive Platt squandered a golden opportunity to mark his first return to London Road since a January transfer to Milton Keynes with a goal.
Tyler was guilty of diverting a Smith centre straight into the path of Platt, but the burly striker sliced his shot from point-blank range into the side netting.
But strike partner McLeod gave a demonstration in expert finishing to clinch three vital points four minutes from time.
McLeod latched on to a slick Wade Small pass and slotted the ball beyond Tyler from 15 yards.
And had it not been for some fine Tyler saves – the best of the bunch a fabulous reaction stop from a glancing McLeod second-half header – pitiful Posh would have been on the receiving end of a real hammering.
Such was the Dons dominance their keeper Matt Baker didn't have a single noteworthy save to make.
Richard Logan wasted Posh's best chance early in the second half when blazing wildly over the bar from the edge of the box.