The heir to the Greggs bakery chain faces jail after he was convicted of indecently assaulting four boys.
Colin Gregg, 75, helped build the family business in the 1960s before becoming a headteacher, social worker and charity boss.
He assaulted his victims - aged between 11 and 14 - over three decades, from the early 1960s to the 1990s.
One victim was abused in a swimming pool and others in a gym and sauna at his home.
Gregg, son of bakery founder John Gregg, had denied all the charges, saying he was the victim of a "witch hunt".
The complainants were looking for compensation, he claimed.
But the grandfather was found guilty of nine counts of indecent assault by a jury at Leeds Crown Court.
The jury was told Gregg was cleared of sexually assaulting a young man in 1997.
The month-long trial in Leeds was a retrial after a jury in Newcastle failed to reach verdicts last year.
Gregg showed no emotion as the verdicts were read out and left the courtroom saying nothing after he was granted bail.
Judge Robin Mairs told him that the fact he was granted bail was no indication of sentence.
He said: "These are serious matters and a custodial sentence is inevitable."
As Gregg left the court building under an umbrella, he was asked if he would apologise to his victims. But he said nothing before being driven away.
The jury had heard how Gregg, of Gosforth, Newcastle, was once headteacher at The King's School Junior School, in Tynemouth.
He also taught at Durham School and was a social worker in Newcastle.
Reports suggest he helped raise millions of pounds for various children's charities.
John Dilworth, from the Crown Prosecution Service, said: "Throughout his life, Colin Gregg has been a successful businessman, respected teacher and committed charity worker.
"Those achievements have won him the gratitude of the community but, beneath his respectable veneer, Colin Gregg was sexually abusing young boys with alarming regularity.
"Colin Gregg exploited his position in society to abuse young boys, using them for his own sexual gratification.
"Working closely with investigating police, we have been able to demonstrate not only a distinct pattern to Colin Gregg's offending, but also a propensity on his part to commit such acts.
"I would like to praise the bravery of the victims in this case. It is thanks largely to their evidence that the court has today found Colin Gregg guilty of nine charges of non-recent sexual assault, charges for which he had evaded justice for a considerable number of years."
Gregg will be sentenced on 30 March.