Joshua was widely acclaimed for his stunning 11th-round stoppage of Wladimir Klitschko in a world heavyweight title bout at London's WembleyStadium on Saturday.
The former Olympic champion victory's was soon heralded as a boxing classic, with the 27-year-old Briton now holding several versions of the world heavyweight title.
"All sports need flag-bearers," said Barry Hearn, the chairman of Matchroom Sport, an agency whose boxing division, headed up by his son Eddie, manages Joshua.
"The Joshua effect is very similar to the Tiger Woods effect in golf, where people who are not so interested suddenly become interested, where young people become aspirational to follow in someone's footsteps," added the 69-year-old Barry Hearn, who made his name managing snooker star Steve Davis before branching out into boxing and darts.
"For that they need a role model and Joshua is the finest role model I have seen in sport, period. He's number one," said the veteran English sports impressario.
"It can also have an effect on other boxers, on the whole concept of boxing as a sport, of the social benefits and of the opportunity that exists for kids that live the right life. On a social level it's a watershed moment in terms of perception for the sport."
Hearn, a lifelong boxing fan, said last weekend's bout was one of the best he could recall and was fit to be ranked alongside the classic 1970s trio of heavyweight fights between Muhammad Ali and Joe Frazier.
"I've been following fights since I was nine years old, listening and studying the game and it delivered on all fronts," said Hearn, who took time out from presiding over snooker's World Championship in his role as chairman of World Snooker, to be at ringside.
"I think it was one of the best heavyweight fights. I always thought Ali-Frazier -- the trilogy was the best, but of course there was only one knockdown in the first one, (the 1971 'Fight of the Century' at New York's Madison Square Garden which Frazier won on points).
"I spoke to (former champion) Evander Holyfield on Saturday night and said to him, 'Can you remember a world title fight when both heavyweights went down?', and between us we couldn't. I was going back in my mind to the Jack Dempsey era (of the 1920s)," said Hearn.