The Latics completed a hat-trick of home wins and believe they can still stage a late challenge to reach the League One play-offs.
Gary McDonald set them on their way before two goals in the last 15 minutes confirmed their victory over a Yeovil side who are in dismal form.
The Glovers created only one clear chance and afterwards their furious manager, Russell Slade, said they could forget about promotion this season.
Oldham took the upper hand with an early goal by McDonald, who bagged his fifth of the campaign from just inside Yeovil's box.
He linked up with full-back Neal Eardley down the right-hand side and hit a sizzling shot which flew inside the far post to give on-loan keeper Scott Flinders no chance.
Oldham youngster Lewis Alessandra fired off target from 18 yards, before Yeovil wasted their one opportunity as substitute Jamie Peters, on for the injured Nathan Jones, was denied by veteran goalkeeper Mark Crossley when he should have scored.
Oldham had a penalty shout for handball against Terry Skiverton in the 59th minute and controlled the tempo of the game with midfielder Mark Allott in outstanding form.
They doubled their lead in strange circumstances after 76 minutes when Alessandra crossed from the right and Lee Peltier headed into his own net from three yards despite having plenty of time to clear the danger.
Oldham's third goal was scored by leading marksman Craig Davies, whose tally in his first season at the club is now 14.
Davies was left with a simple tap-in from a couple of yards after being set-up by Alessandra and substitute Deane Smalley.
Oldham have lost only three of their last 18 league matches as they bid to clinch a play-off spot for the second consecutive year.