The winner of the first series of The Apprentice has left the £100,000-a-year job he landed after the show, working for Amstrad boss Sir Alan Sugar.
Sir Alan has called Campbell "a role model for young people"
Sir Alan said former London Underground manager Tim Campbell, who was kept on after the end of his original 12-month contract, had been a "great asset".
Campbell is planning a male grooming business and an initiative that will give £1m a year to entrepreneurs.
The third series of The Apprentice starts on BBC One on 28 March.
The show sees aspiring businessmen and women taking on tasks set by Sir Alan, who dismisses losing candidates with his "You're fired" catchphrase - until one winner remains.
Campbell won the 2005 series, landing a job in Amstrad's health and beauty division.
"He was the right choice and I will be there to offer help and guidance should he need it," said Sir Alan.
Campbell said the Amstrad boss had been "inspirational" and taught him "how to take risks".
"More importantly, he has built my self-confidence and taught me practical skills that have helped me to look at new challenges."
He added: "Now I want to share what I have learnt with others, as well as grow my own company. I'm relishing my future."
Campbell is planning to launch the Bright Ideas Trust, with the aim of giving away £1m to 250 new businesses every year.
"I want the trust to unleash a wave of creativity among people in the UK," said Campbell.
Last year's winner of The Apprentice, Michelle Dewberry, left Amstrad within months.
At the launch of the third series on Tuesday, Sir Alan said he had been "disappointed with the calibre of the contestants" in 2006.
But he promised "tougher tasks, better people performing them" in the new series.
Last year's series finale achieved viewing figures of 5.7 million, prompting the programme's move from BBC Two to BBC One. The series also won a TV Bafta.