The comic has quit after just one year hosting the show, taking over the BBC Two series from fellow funnyman Dara Ó Briain last series.
In a statement released today, Jack confirmed his exit and said it was due to other work commitments.
"It's been a tough decision to leave You're Fired," he commented. "I'd like to thank The Apprentice team, BBC Two, the candidates and the 'Big Man' Lord Sugar himself for making me feel so welcome but now, in keeping with The Apprentice tradition, I am firing myself. Good luck with the next series."
BBC Entertainment boss Alan Tyler said: "Jack is one of the most talented comedians in the UK and he very quickly made You're Fired his own.
"We are really sorry to see him go but we are also delighted to be working with him on a number of other projects."
There's been no word yet on any replacements with the new series of The Apprentice a long way off right now.
With both Euro 2016 and the Olympics in the summer, The Apprentice 2016 start date isn't expected until the autumn.