The actors previously starred in CBS sitcom Yes, Dear, which was created by Raising Hope's Greg Garcia and the late Alan Kirschenbaum.
The pair will play a couple who discover an old sex tape recorded by Burt (Garret Dillahunt) and Virginia (Martha Plimpton) many years ago, reports Entertainment Weekly.
"As one of the world's biggest Yes, Dear fans, I am very excited about this reunion," said Raising Hope executive producer Garcia.
He added: "I can't wait to work with Mike and Liza again. Two incredibly funny people who turn my tin cans into gold every time."
O'Malley and Snyder previously portrayed married couple Jimmy and Christine Hughes on Yes, Dear for six seasons until 2006. O'Malley currently recurs in Fox's Glee.
Raising Hope will return to Fox on January 8 at 8pm ET, which will feature a guest appearance from Christopher Lloyd.