Jonathan Forte and Mike Jones made it 2-0 for Latics before Andy Halliday reduced the arrears before half time.
Rory McArdle saw red for the visitors deep into the second half and the home side held on as they made it 13 games unbeaten in all competitions.
The home side got off to a blistering start as the forward three of Forte, Danny Philliskirk and Jabo Ibehre causing a nuisance in attack.
After retaining possession for the early proceedings, Latics took the lead on seven minutes through Forte.
Joseph Mills crossed for Ibehre in the centre who nodded the ball down to the 28-year-old and he stabbed the ball into the top corner to score his 11th goal of the season.
The fans, who turned up in their droves, were playing a huge part in the game as they sang from start to finish.
Latics' defence had to be aware on 13 minutes as Mark Yeates found a sight of goal but goalkeeper Paul Rachubka saved well.
Athletic were enjoying a lot of the ball and almost doubled their lead on 22 minutes as Philiskirk fired straight at Bradford stopper Jordan Pickford.
It did not take long for the home side to extend their lead two minutes later. Carl Winchester won the ball in the middle of the park, sprayed it out wide to Jones and he was allowed the freedom to shoot from the edge of the box to double Latics' lead.
The home side were in cruise control and minutes after the restart, an error in the Bradford box almost allowed Forte to capitalise but Pickford saved well.
Ten minutes before the break, Liam Kelly sized one up from 35 yards but his curling shot was well tipped over the bar by the Bradford goalkeeper.
Just as Latics looked to be going into the break two goals to the good, the Bantams managed to find away back into the game.
Halliday was allowed enough space inside the area to volley past Rachubka and the score was 2-1 at half time.
Latics did not let that goal affect them as they came out for the second half. Mills' turn of pace and cross picked out Forte in the centre but his header went wide.
Only a minute later, Philliskirk smashed the ball over the bar on the volley after a great ball into the box by Jones.
Just before the hour mark, the 23-year-old again volleyed from the edge of the box but Pickford was behind the shot and saved well.
Bradford started to come back into the game and Latics had to defend resolutely as the game turned into a thrilling contest.
After a string of penalty decisions were turned down for the away side, Athletic raced up the other end but Philliskirk could not test Pickford as he raced through on goal.
Athletic started to get their foot back into the game and with only 20 minutes of the game were unfortunate not to extend their lead. Jones' run took him to the byline and he cut the ball back for Forte who prodded it goalwards but out of nowhere Pickford managed to save.
Both Winchester and Forte were substituted to a standing ovation from the home fans as time ticked away.
On 75 minutes, Rachubka had to palm away a shot from former Latics loanee Alan Sheehan as the game started to open up.
With both sides having chances, the game was on a knife-edge. Ibehre, who had been superb all afternoon, held the ball up well in attack as he eased the pressure on Latics' defenders.
Bradford piled everything forward in search of an equalising goal but Latics were standing form with Rachubka marshalling his defence well.
Into added on time, the Bantams were reduced to ten men as McArdle was sent off for two bookable offences. The defender brought down Ibehre on the edge of the box and he was given his marching orders.
The visitors threw everything forward as Pickford joined the attack for a last minute corner but Timothee Dieng headed the danger away to seal the three points for Latics.
Oldham Athletic: Rachubka, Kusunga, Dieng, J.Wilson, Mills, Kelly, Jones, Winchester (Dayton 73'), Forte (Poleon 76'), Philliskirk, Ibehre.
Subs not used: Brown, Turner, Tyson, Mellor, B.Wilson.
Bradford City: Pickford, Darby, Sheehan, Liddle, Hanson, Yeates, Stead, Kennedy (Knott 73'), Routis (Meredith 39'), McArdle, Halliday (Clarke 79').
Subs not used: Williams, Dolan, McLean, Morais.
Goals: Oldham Athletic (Forte 7', Jones 24') 2-1 Bradford City (Halliday 45+2')
Attendance: 5,832 (1,510 visiting supporters)