Midfielder Wallwork, on loan from West Bromwich Albion, joined the Terriers at the end of last month.
He had been sidelined since being injured in a stabbing incident at a Manchester nightclub last November and is bidding to kick-start his career.
The headed equaliser, nine minutes from time, was nothing less than Huddersfield deserved for a powerful second-half display.
They struggled to get to grips with a slick Oldham side in the first half with a series of aimless long balls.
They were booed off at the break after going behind to Craig Davies' sixth goal of the season in the 27th minute.
Welsh international Davies, a £65,000 summer signing for boss John Sheridan, cashed in on defensive uncertainty to fire a looping drive over the head of keeper Matt Glennon.
Chris Taylor's deflected through ball was headed out by Richard Keogh and Davies collected it and beat Nathan Clarke before spotting Glennon off his line.
Huddersfield were much improved in the second half and the Latics needed veteran keeper Marlon Beresford to keep them in the game.
Beresford, 38, making his debut on loan from Luton, tipped a shot from Frank Sinclair wide.
From the resulting corner Beresford clawed away a Wallwork effort.
Danny Cadamarteri lifted a shot over the bar from eight yards, but had been ruled offside. Beresford then twice denied Cadamarteri from close range.
Oldham had a chance to seal it but Reuben Hazell's header was narrowly wide and Matty Wolfenden skipped through Town's defence only for Glennon to save, but he almost blotted his copybook by letting the ball squirm from his grasp.
The home side grabbed a point when Cadamarteri sent over a teasing cross from the left and Wallwork came flying in at the back post to head powerfully past the helpless Beresford.