Daniel Johnson opened the scoring in the first half before Jonathan Forte tucked away a penalty on 70 minutes after Danny Philliskirk was pulled down in the penalty area.
Johnson rounded off the scoring on 80 minutes knocking the ball comfortably past the goalkeeper to seal three points for Latics and make that one defeat in 19 games.
Both sides entered the field to a cauldron of noise as over 3,000 Latics fans had made the journey to the game.
They were almost rewarded in the opening minutes of the game but Brian Wilson's cross could not find a Latics man in the box and the ball went out of play.
On the fourth minute, both sets of supporters joined together to remember the late Ernie Cooksey who sadly passed away in 2008.
On the field, Liam Kelly fired a volley wide of goal on six minutes as the visitors were knocking on the door of an opener.
Rochdale started to come back into the game and went close ten minutes later. Jack Muldoon was slipped in but as he raced through on goal, his cross could not pick out a man in the box.
Reuben Noble-Lazarus, Scott Tanser and Matthew Lund were all creating chances for the home side but could not find a clear cut goal scoring opportunity.
Latics took the lead on 24 minutes through Johnson. Danny Philliskirk slipped the ball through to the forward and he saw his initial shot saved by goalkeeper Conrad Logan but the ball ricocheted back into his path and he stroked into an empty goal to send the supporters into delirium.
James Wilson was the first player to be given a yellow card on the half hour mark for a foul on Stephen Dawson.
Latics continued to attack and almost doubled their lead through Mike Jones. The loose ball was bouncing around in the box and the midfielder stuck but Logan's strong palms denied him.
Rochdale broke and Jamie Allen almost brought the visitors level but the ball sailed inches past debutant Paddy Kenny's goal.
Seconds after the break, the home side forced Kenny into action for the first time as Ian Henderson's header was comfortably saved by the goalkeeper.
Just as Rochdale have an appeal for a penalty turned down, Latics broke and Philliskirk fed Forte but the forward was dispossessed. The ball fell for Kelly but he ballooned his shot over the bar without troubling Logan.
On the hour mark, Kenny was again forced into making a save from Noble-Lazarus. The youngster was given freedom on the edge of the box but the experienced stopper pulled off a good save to keep the scores level.
The home side were gaining the ascendancy as Tanser was finding a lot of space on the right-hand side but the Athletic defenders held their ground well and cleared the danger.
Latics were awarded a penalty on 70 minutes as Noble-Lazarus pulled back Philliskirk in the box and the referee had no hesitation in pointing to the spot.
Forte stepped up and smashed the penalty down the middle which gave Latics a 2-0 lead.
The visitors were in control and almost extended their lead on 75 minutes. Philliskirk found space inside the box but Logan saved his shot comfortably.
The striker was causing Rochdale problems and he provided the ball for Johnson to score the third.
He nicked the ball off the defender and fed the onrushing loanee and he tucked the ball comfortably under the goalkeeper to put the game beyond doubt.
Into the final ten minutes of the game, Latics welcomed back defender George Elokobi for his first appearance since the end of September.
Rochdale went close in added time but substitute Calvin Andrew could only head wide from Henderson's cross and the forward struck a free kick over the bar.
But it was Latics that ultimately came away with victory which moved them into the play off positions.
Rochdale: Logan, Bennett, Eastham, Lund, Noble-Lazarus, Dawson (Cwyka 73'), Tanser, Muldoon (Andrew 73'), Allen (Hery 73'), O'Connell, Henderson.
Subs not used: Lancashire, Diba Musangu, Rose, Cannon.
Oldham Athletic: Kenny, B.Wilson, J.Wilson (Elokobi 87'), Kusunga, Mills, Dieng (Tidser 89'), Kelly, Jones, Johnson, Philliskirk, Forte (Poleon 81').
Subs not used: Rachubka, Dayton, Winchester, Morgan-Smith.
Goals: Rochdale 0-3 Oldham Athletic (Johnson 24', 80', Forte 72')
Attendance: 7,269 (3,250 visiting supporters)