It was the first time the Dons had registered back-to-back wins this season and saw them climb out of the League Two relegation zone, leapfrogging above Bristol Rovers and Plymouth in the fight for Football League survival.
McCallum, on loan from West Ham, bagged the winner in the 58th minute and the Dons held out comfortably for the win after Dale were reduced to 10 men with Joe Rafferty's dismissal for a second bookable offence.
"Paul got sent off in his first game for us, so missed the next three, which was hard for him," said Ardley, who signed the frontman in November.
"He needed a bit of time to adapt. Now he's adjusting to the pace and the work ethic we need while we're down the bottom.
"He's slowly getting there. The more he holds it up, the more chance we've got of delivering quality for him and the more chance he's got of getting on the end of them."