Caulfield is to appear on the Jan. 15 episode of the fairytale-themed series, the network said.
The installment will be a retelling of the Hansel and Gretel legend.
"Once Upon a Time" stars Ginnifer Goodwin as Snow White/Mary Margaret, Jennifer Morrison as Emma Swan, Robert Carlyle as Rumplestiltskin/Mr. Gold, Lana Parrilla as Evil Queen/Regina, Jared Gilmore as Henry Mills, Josh Dallas as Prince Charming/David and Raphael Sbarge as Jiminy Cricket/Archie Hopper.
Celebrity Breakups and divorces of 2014 [PHOTOS]