Latics, who had had not won in their nine previous games, put up a gritty performance at Boundary Park against play-off chasing Bradford and were rewarded with three points in their battle against relegation.
Oldham into a 12th-minute lead when full-back Cameron Dummigan ran at the Bradford defence and blasted a 25-yard drive into the top corner.
Dan Gardner nearly added to the score midway through the first half, but was foiled by Bradford goalkeeper Colin Doyle who tipped his effort over the bar.
The Bfradgord keeper also denied Wolves loanee Duckens Nazon after the striker burst clear and fired towards the bottom corner.
Oldham made it 2-0 after 86 minutes when Ryan McLaughlin crossed from the left and Aaron Holloway headed in from eight yards.
There was a late rally from Bradgford but latics held on to chalk up their first victory of 2018.