Goals from Will Grigg and a brace from strike partner Michael Smith did the trick as the Millers made it three games unbeaten.
Millers boss Paul Warne made three changes to his side which drew with Crewe at the weekend, with Michael Ihiekwe recalled in a defensive reshuffle.
Sunderland loan hitman Grigg headed the home side ahead nine minutes before the break with a thumping finish from Shane Ferguson’s pinpoint cross.
It was Grigg’s first goal for his new loan club and then it got even better for the hosts as Smith pounced to score his seventh goal of the season.
The tall centre-forward timed his jump to perfection, powering midfielder Dan Barlaser’s corner beyond Dons’ keeper Nikola Tzanev.
And Smith completed a fine evening at the office when he bagged his second goal with a minute remaining.
Smith rifled home right-footed after Ben Wiles’ set-piece had cause the visitors all sorts of problems. Daniel Csoka wasted a glorious chance to pull a goal back for the Dons, but missed from close-range.
Rotherham: Johansson, Edmonds-Green, Wood, Ihiekwe, Barlaser (Odoffin 85), Ogbene, Lindsay (Wiles 58), Rathbone, Ferguson, Smith, Grigg (Kayode 66). Unused substitutes: Sadlier, Ladapo, Bola, Vickers.
Wimbledon: Tzanev, Nightingale, Heneghan, Csoka, Lawrence, Woodyard, Marsh (Hartigan 75), Osew (Mebude 55), Chislett (McCormick 68), Pressley, Rudoni. Unused substitutes: Alexander, Guinness-Walker, Oualah, Charles.
Referee: A Haines (Tyne & Wear)