Joshua, 23, needed just two minutes and 47 seconds to stop previously unbeaten Italian Emanuele Leo on Saturday night at London’s O2 Arena.
“It was just as important as winning the Olympics because everyone is here to support and everyone is proud that we got the victory,” said the Watford fighter.
“Winning the Olympics was a priceless experience as well and this is my pro debut, there’s only one pro debut and we ended it in spectacular fashion. It’s just onto the next one now.”
Joshua, who has set himself the target of becoming world champion within four years, could fight twice more this year, with his next contest set to be in Sheffield later this month.
Earlier in the evening fellow London 2012 gold medallist Luke Campbell knocked out Neil Hepper in the first round of his second professional bout.