The 28-year-old Fresh Meat actor will play a maths teacher in the sitcom's series two premiere, which airs tonight at 9.30pm.
The episode - which sees Mitch (Stephen Wight) decide to return to life as a student and resit his exams - also features a guest appearance from Outnumbered's Tyger Drew-Honey, who plays a school bully.
The new series of Threesome follows Mitch, Alice (Amy Huberman) and Richie (Emun Elliott) as they attempt to raise their newborn baby.
Huberman recently told Digital Spy that series creator Tom MacRae has "come up with a really original and really funny way of looking at new parenting that isn't [what] you would expect".
"It's just seeing how they do deal with parenthood, but they've done it in a way that it isn't regular clichés," said the actress.
