Joshua, who won boxing gold as a super-heavyweight at London 2012, brought the curtain down on his amateur career after putting pen to paper on a long-term professional contract with Matchroom.
And Hearn, who announced the Watford-born fighter will headline the Carpe Diem bill featuring Lee Selby and Kevin Mitchell at the O2 in October, predicted big things for Joshua.
“This is something very special for British boxing,” said Hearn.
“Finally I believe we have got a heavyweight in this country that we can get very very excited about.
“For me Anthony Joshua has got it all. He’s got speed, he’s got power, he looks the part, he talks the part.
“I think we’ve got the perfect ambassador not just for British boxing but for British sport.”
Joshua believes his 43-fight amateur career which culminated in Olympic gold in London is the perfect platform to embark upon the next stage of his fight career.
“It’s given me the foundation to move into the professional ranks,” he said.
“This is just the beginning. It’s going to be a very tough road, but I’m so determined and I know what I need to do to make my dreams come true.
“I’m willing to sacrifice anything I need to sacrifice to create this destiny and make everyone in Britain proud.”
The 23-year-old will be trained by Tony Sims and is expected to fight at least three times before the end of the year.
Joshua was introduced to boxing only 5 years ago by his cousin Ben Ilyemi , himself an ABA champion.
The pair learned their trade at Finchley Amateur Boxing Club which has produced world-class fighters including Spencer Oliver, Derek Chisora and Darren Barker.
Tickets for Anthony Joshua’s debut ‘Carpe Diem’ are on sale now priced £40, £60 and £100.
VIP packages priced £200 are exclusively available from Matchroom Sport on 01277 359900 or at www.matchroomboxing.com.
image: © KWDesigns