Rotherham substitute Kieran Agard headed home the only goal of the game as the Millers returned to winning ways at AFC Wimbledon.
Wimbledon had the better of the first half with Steven Gregory heading into the side netting and Will Antwi almost bundling over a Stacy Long corner.
Rotherham striker Daniel Nardiello went close when firing wide following keeper Neil Sullivan's weak punch.
But Agard won it after his header hit the post and bounced in off Sullivan.
VIEWS FROM THE DRESSING ROOM
Rotherham United manager Steve Evans told BBC Radio Sheffield:
"It was hard fought wasn't it.
"There was nothing in the first half, both teams seemed to cancel each other out.
"I think second half we've absolutely dominated in their half, apart from one chance they should have scored."