Reece Burke gave the Bantams a first half lead before Jonathan Forte saw red for an apparent headbutt on Bradford’s Stephan Darby.
Devante Cole doubled the Bantams lead in the second half before Joseph Mills pulled a late goal back for Athletic but it was not enough.
Manager Darren Kelly made six changes to his starting line up that lost 2-0 at Shrewsbury Town on Tuesday night.
One of those The visitors started the game brightly with Josh Morris’ free kick almost catching goalkeeper Joel Coleman off guards but he did well to recover and tip around the post.
Latics started to come back into the game and Mike Jones’ dangerous corner into the box caused problems for Bradford City but Jonathan Burn’s goal bound shot was blocked.
Athletic were keeping the ball comfortably in midfield but Danny Philliskirk was booked on 15 minutes for a late challenge on a Bantams midfielder.
David Dunn was using his experience in the middle to keep possession and on 20 minutes he won a free kick in a good position for Latics.
Jones stood over the ball but goalkeeper Ben Williams was equal to his effort.
The Bantams took the lead on 21 minutes in controversial circumstances through central defender, Burke.
Coleman looked to be fouled as a free kick was whipped into the box. Whilst on the floor, the game continued and Burke, on loan from West Ham, slotted the ball into an empty goal to give them the lead.
Mark Yeates, playing against his former club, received a lot of the ball on the right hand side and caused his defender problems in the opening 30 minutes.
After the half hour mark, Latics were reduced to ten men after the referee spotted an off-the-ball incident between Forte and Bradford full back Stephan Darby and Forte was sent off.
Latics needed a lift but the visitors continued to put the pressure on with Billy Knott shooting narrowly wide from 30 yards.
Coleman had to be alert before the half time break as Hanson headed from six yards but the goalkeeper pulled off a wonder stop to deny the forward.
Athletic brought on Rhys Turner in place of Timothee Dieng at half time in a bid to get more attacking players on the pitch.
That change did seem to lift Latics as they started the second half strongly and went close on 52 minutes.
Danny Philliskirk, who pushed into a more attacking role after Forte’s sending off, shot over the crossbar whilst Dunn’s attacking run and shot was well saved by Ben Williams.
Just after the hour mark, Yeates, who was still causing problems on the right, cut inside and won a free kick in a dangerous area.
He picked himself up to take the free kick and forced Williams into a diving save as Latics pressured the Bantams goal.
Only a minute later, Bradford extended their lead through striker Cole.
Knott threaded a perfectly-weighted through ball to the onrushing striker and he placed it past Coleman to put the visitors two goals ahead.
That goal seemed to knock the stuffing out of Latics as the visitors started to dictate the game and looked comfortable in possession.
Rhys Murphy was introduced with 20 minutes of the game remaining and he headed over from a Yeates cross on 78 minutes as Latics looked to pick themselves up.
On 82 minutes, they did manage to pull a goal back through full back Mills.
It was a cross from the excellent Yeates to the back post and Mills, who was unmarked, guided the ball home to make it 1-2.
Latics started to huff and puff to get something out of the game with Murphy again having a header saved by Williams and Carl Winchester curling a shot just wide of the goal.
That was the best it got for Latics as they were consigned to their first league defeat of the season.
Oldham Athletic: Coleman, Mills, Wilson, Burn (Murphy 70’), O’Connell, Dieng (Turner 46’), Jones, Yeates, Philliskirk, Dunn (Winchester 79’), Forte.
Subs not used: Brown, Cornell, Edmundson, Tuohy.
Bradford City: Williams, Darby, McArdle, Burke, Meredith, Marshall (Anderson 84’), Liddle, Knott (McMahon 89’), Morris, Hanson, Cole (James 76’).
Subs not used: Jones, N Clarke, Leigh, Davies.
Goals: Oldham Athletic (Mills 82’) 1-2 Bradford City (Burke 21’, Cole 63’)
Attendance: 5,619 (1,665 visiting supporters)