The Irish star played the dual roles of Sheriff Graham / the Huntsman in the ABC fantasy drama's first season.
© ABC
Though the Graham character was killed off, Dornan told Digital Spy that he "wouldn't be shocked" to see his Huntsman counterpart reappear in the future.
The 30-year-old actor has now been confirmed by ABC to be returning to Once in a forthcoming episode.
Alphas star John Pyper-Ferguson also recently signed up for a role on the series - the Caprica veteran will play Ben, a widower trying to help his son (Benjamin Stockham) overcome the loss of his mother.
Jamie Dornan will next be seen in BBC Two crime thriller The Fall opposite X-Files actress Gillian Anderson.
Once Upon a Time will resume its second season on February 10 on ABC and will return to Channel 5 in the UK later this year.
> Heroes star Rena Sofer to play Snow White's mother on Once Upon A Time
Watch a promo for the return of Once Upon a Time below:
