Sam Winnall gave the Tykes the lead during additional time in the first half, whilst Curtis Main equalised with 20 minutes of the game to play.
With both sides pushing for a winner, it would be the home side which got it as Tareiq Holmes-Dennis brought down Adam Hammill to win Barnsley a penalty.
Winnall stepped up and sent Coleman the wrong way to win the game for the Tykes, ending Athletic’s four game unbeaten run.
Manager John Sheridan made two changes to his side as Carl Winchester replaced Matt Palmer who returned to Burton Albion yesterday and Jake Cassidy replaced Jonathan Forte.
It was a fast start to the game with both sides having attack after attack.
Latics had the first opportunity of the game as Mike Jones got to the byline, cut the ball back to Main but his flick just went the wrong side of the post.
Barnsley broke up the other end and an Hammill cross was headed wide by Winnall, but the linesman’s flag was up anyway.
The Tykes were proving to be a threat from set pieces and minutes later Alfie Mawson headed wide from a Conor Hourihane free kick into the box.
Athletic looked promising on the break with Main a constant threat.
Firstly he skipped past the defender, cut the ball back to Carl Winchester to strike but his shot was blocked.
A minute later, it would be the Doncaster Rovers loanee that tested the palms of Barnsley goalkeeper Adam Davies from 25 yards.
Winchester sized up a shot from 25 yards which was scuffed wide, however five minutes later the midfielder had to be replaced after picking up a suspected knee injury.
Brian Wilson replaced the midfielder but his evening would only last six minutes as he was stretchered off due to a head injury.
Winnall received space in the centre, struck the post but in trying to defend the ball, Coleman’s knee collided with B.Wilson’s head and he had to be stretchered off.
It would be a long delay as the defender received the treatment he needed, slowing the pace of the game right down.
Sheridan was forced to reshuffle his pack for the second time as Jonathan Forte took his place, moving to left wing, Main moved out onto the right-hand side and Cassidy played as the lone striker.
That move almost saw Latics open the scoring on 40 minutes as Main fed the onrushing Liam Kelly but his tame shot was easily saved by Davies.
It wasn’t just Athletic who were suffering with injuries as Barnsley were forced to make a change before the break with George Williams replacing James Bree.
Main again was at the centre of the action as the fourth official announced nine minutes of additional time to be played.
He played a neat one-two with Kelly and fed Cassidy through on goal but the ball just ran away from the striker.
Minutes later, he won the ball at the back, drove forward and played the ball to the feet of Forte but he could only win a corner.
However, it would be Barnsley who took the lead before the break from a set piece.
Hourihane’s corner was powerfully headed home in the middle by Winnall to give the Tykes the half time lead.
Sheridan made his final substitution of the game on half time as Mike Jones, who went down with an injury in the first half, was replaced by Jack Tuohy who was making his first league appearance of the season.
In the early stages of the second half, Barnsley almost grabbed a second courtesy of Ivan Toney but the linesman’s flag was up to deny the striker a goal.
The referee was making himself unpopular with the Oldham Athletic players and supporters after booking Anthony Gerrard and Coleman within a two minute period.
The goalkeeper was booked along with Winnall for an altercation in the penalty box.
Just before the hour mark, Tuohy struck over the bar whilst five minutes later, great play from Main saw him skip past three men before unleashing a powerful strike just wide of the goal.
That would be a sighter for the striker as on 68 minutes he would find the equaliser.
Kelly’s pass from the middle of the park found Dummigan on the right who crossed into the centre. The ball found its way to the back post where Main was stood and he converted from 12 yards to get Latics back into the game.
All of Athletic’s good work was almost undone moments later as Winnall beat the offside trap and smash goalwards. Luckily he found an in-form Coleman between the sticks and the goalkeeper palmed onto he post.
Another let off followed as a long throw in into the box was not dealt with but Winnall missed his kick and it allowed Coleman to grasp.
The home side were really piling the pressure on Latics and on 83 minutes won a penalty after Tareiq Holmes-Dennis tripped the onrushing Hammill.
Winnall stepped up and sent Coleman the wrong way to put the Tykes ahead.
Latics continued to push for another equaliser with Forte going close in the dying minutes but it would be Barnsley that came away with the victory.
Barnsley: Davies, Bree (Williams 42’), Roberts, Mawson, White, Watkins (Scowen 87’), Hammill, Hourihane, Brownhill, Toney (Fletcher 65’), Winnall.
Subs not used: Townsend, Nyatanga, Chapman, Isgrove.
Oldham Athletic: Coleman, Dummigan, Gerrard, J.Wilson, Holmes-Dennis, Dieng, Kelly, Jones (Tuohy 46’), Winchester (B.Wilson 20’, Forte 33’), Cassidy, Main.
Subs not used: Cornell, Brown, Mills, Croft.
Goals: Barnsley (Winnall 45’, 83’) 2-1 Oldham Athletic (Main 68’)
Attendance: 8,871 (526 visiting supporters)