The 27-year-old has found first-team opportunities to be limited at Deepdale this campaign.
Latics boss Lee Johnson told the club's official website: "Joel's come in to bolster us and adds a bit of experience at this level which is something we need."
Also speaking to www.oldhamathletic.co.uk, Byrom added: "It's a good move for me. I know a few of the players here so it's a good team to come into.
"I'll bring a bit of balance to the team with my left foot. I like to keep the ball, create chances and hopefully I can nick a goal or two."
Meanwhile, the Latics have also signed Norwich defender Adel Gafaiti on loan until April 21.