Even a hat-trick from transfer-listed striker Damian Spencer could not lift the Robins, who are now without a win in nine league and cup matches and sank to the bottom of the League One table as other results went against them.
Dons striker Aaron Wilbraham bagged a hat-trick and winger Jemal Johnson scored twice as the visitors built up a 5-1 lead before a late Cheltenham revival.
Cheltenham started well enough with Ian Westlake forcing Dons goalkeeper Willy Gueret into a fine save with 14 minutes played.
That was only a minute after Sam Baldock of Milton Keynes had drawn a good stop from Scott Brown at the other end.
It was not long before the visitors took the lead as wideman Jemal Johnson collected the ball midway inside the Cheltenham half.
He dribbled forward and cut inside onto his left foot before blasting a 25-yard shot inside Brown's left-hand post.
Cheltenham continued to press forward and Gueret palmed a shot from Lee Ridley over the bar, but the Robins were frail at the back and it showed in the moments leading up to half-time.
Just a minute before the break, a left-wing cross from Johnson caught Brown in two minds, the ball rebounded off defender Chris Westwood and straight to Wilbraham, who made no mistake.
Two minutes into added time, Wilbraham was on target again as this time a right-wing cross from Luke Chadwick was touched into his path by Baldock and the big frontman did the rest from close range.
Wilbraham completed his 15-minute hat-trick when he controlled a left-wing cross from Jason Puncheon inside the area before drilling a shot past Brown.
Cheltenham pulled one back when Spencer - a half-time substitute for Josh Low - drove a shot through a crowd of players from a tight angle, although Johnson made and scored his team's fifth when a Cheltenham free-kick was headed clear to the edge of the Milton Keynes penalty area.
Johnson sprinted virtually the whole length of the pitch before planting a shot beyond Brown.
After that there was still plenty of time for Spencer to score twice more and get himself sent off.
The powerful frontman drove in from a Nicholas Bignall cross on 75 minutes then converted a penalty after Lloyd Owusu had been fouled.
Five minutes from time an eventful game was completed when Spencer was given a red card by referee Kevin Friend for a heavy challenge on Dean Lewington.