The claim was the latest in a string of anti-Brexit tirades from the billionaire Virgin tycoon who claimed leaving the bloc would be “the saddest thing that has ever happened to Europe”.
Mr Branson, who lives in the British Virgin Islands, suggested people who voted to leave were older Britons who would pass away in the next few years.
He told RTE: “The older generation is dying off.
“So whether there’s a second referendum before Brexit happens – I’m sure the Tory party will do their best not to allow that to happen – but I think within five years there will be a government in power in Britain that will ask Europe for a chance to let Britain re-enter.
“Because there will be so many young people who will be a little bit older by then and so many of the older grandparents who voted for Brexit will have died off, I think that Britain will become part of Europe again.”
His comments have caused outrage on social media with people hitting out at the “self-serving” businessman and some even calling for a boycott of his company’s services.
Brian Berridge raged: “So the success of Brexit depends on whether we live or die anytime soon.
“Chances are Mr Branson we could see you out.”
And Gordon Grove tweeted: “What a disgraceful way to look at this. Boycott all his brands.”
Another tweeter wrote: “Branson doesn’t even live in the UK.
“Who the hell is he to tell us. Brexit is actually making UK better.”
And another Brexit supporter predicted: “The EU will die before we do.”
Others branded his argument “shameful” and accused him of being arrogant and out of touch.
During his interview, the 67-year-old also lashed out at Brexit campaigners like Boris Johnson.
He accused the Leave campaign of a “ghastly misrepresentation of reality” for its claims during the referendum.
And he complained: “Britain was doing really well before the Brexit announcement.
“Since the Brexit announcement, we’ve dropped to the bottom fall European countries, as far as Brexit is concerned, and this is just a taste of what is going to happen.
“I think Britain is going to continue sliding down and down. That’s very sad.”