Two penalties from Chuks Aneke and Kieran Agard condemned Latics to a third straight defeat at the Stadium MK.
Tom Hamer pulled one back for Latics with a superb volley, but it wasn’t enough to spark a comeback for Oldham.
MK Dons started the game sharper than Latics, but it seemed their route to goal would come from a set piece as Joe Walsh twice headed wide from a corner.
Another corner for the home side fell to Ryan Harley on the edge of the box, but he curled his effort over the bar.
However, the home side took the lead as Dean Lewington went down under a challenge from Christopher Missilou with referee Antony Coggins pointing to the penalty spot.
Aneke stepped up and sent Daniel Iversen the wrong way to give his side the lead.
In fairness the goal seemed to be the spark Latics needed as Missilou’s effort made goalkeeper Lee Nicholls almost spill the ball into the path of Callum Lang.
Latics created a couple of half chances as Lang saw a shot in front of goal before Urko Vera hit an acrobatic effort wide.
Baily Cargill forced Iversen into a decent save before Lang hit an effort just wide for Latics.
Vera had a good chance from a corner which was flicked into his path by Tom Hamer, but MK Dons got bodies in the way of the Spanish striker’s shot.
Missilou hit a volley straight down the throat of Nicholls, before Watson tested Iversen after a neat move down the right as the home side went in one up at half time.
Vera almost had Latics level at the start of the second half as Gevaro Nepomuceno’s cross was pulled back by Lang, but Nicholls saved from Vera from around three yards out.
Mohamed Sylla then had a shot deflected inches wide as Oldham were starting to get on top in the contest.
However, substitute Jose Baxter brought down Alec Gilbey in the penalty area and the home side were awarded another penalty.
Agard stepped up this time and placed it straight down the middle to doubles the hosts lead.
However, almost immediately Latics pulled one back as the ball fell to Hamer on the edge of the box and his left-foot volley flew into the top corner.
MK Dons were sitting back and hitting Latics on the counter attack as Pete Wild’s men struggled to create chances for an equaliser.
Baxter did hit a freekick just over the bar, but that’s as good as it got for Latics as they fell to yet another defeat at the Stadium MK.
Attendance 5950 (TBC Away)
Nicholls, Lewington ©, Walsh, Watson, Gilbey, Aneke (Sow 71’), Agard (Houghton 68’), Martin, McGrandles, Cargill, Harley (Wheeler 53’)
Iversen, Hamer, Edmundson ©, Stott, Nepomuceno, Lang (Dummigan 85’), Missilou, Sylla (Baxter 62’), Branger-Engone, Maouche, Vera (O’Grady 62’)