The three first-half goals conceded by the Canaries were all well made and executed.
However Norwich's Steen Nedergaard might well have made things different, had he found success with a ninth minute effort when he failed to beat the keeper from just five yards out.
The Dons took the lead when Jermaine Darlington crossed from the left and Neil Shipperley controlled the ball and sent a deflected volley past Robert Green.
A David Connolly brace then gave Wimbledon a comfortable half time lead.
First, in the 41st minute, he took the ball into the City box and comprehensively beat Green with a low shot.
Then, four minutes later, Green picked the ball out of the net again after Connolly's 25-yard free kick rifled through the five-man wall
Although the Dons dominated for long periods of the second half the Canaries fought back to 3-2, only for an 81st minute penalty to sink their comeback.
Substitute Ian Henderson had only to run on and beat Kelvin Davis after latching on to a 69th minute clearance.
Nedegaard had a 70th minute header hacked off the line by Trond Andersen before substitute David Neilsen claimed City's second. It was Nedeagaard's cross from the left that was steered perfectly home from close-range.
Nine minutes from time the result was put beyond all doubt.
Nigel Reo-Coker put a ball into the box from the right and Connolly and Malky Mackay contested the cross, only for the referee to point to the spot.
David Connelly took the penalty, driving it well out of the goalkeeper's reach, to claim his hat-trick and twelfth goal of the season.
Its only one defeat in seven games for the Dons and on this performance Milton Keynes will be welcoming a first division outfit next season.