The comedian will hold court on the BBC Two discussion show, which sees the host joined by a celebrity panel as they grill the latest contestant to be fired by Lord Sugar on the business-based reality show.
Jack said in a statement: “I’m very much looking forward to hosting ‘You’re Fired’ and hope that the luckless candidates will see me as the friendly face at the end of a difficult time in their lives.”
Comedian Romesh Ranganathan has also been promoted to a regular panellist, and will help Jack interview the contestants on each episode.
Dara announced he was quitting ‘You’re Fired’ in January, after five years in the role.
He said at the time: "I've decided to pass the chair on to someone else. In that time I've interviewed 84 wannabe apprentices.
"If I interview any more, I'll turn into Claude Littner. Mainly though, I'm back on tour again this year and I'd like to enjoy getting laughs off my own incompetence for a while.”
He took over from previous host Adrian Chiles in 2010, when the presenter was forced to quit due to his new deal with ITV.
Jack already has a history with ‘The Apprentice’, having appeared on a celebrity edition for Comic Relief back in 2009.
‘The Apprentice’ is expected to return to BBC One next month, when Claude Littner will replace Nick Hewer as one of Lord Sugar’s advisers.