The hurricane has left apocalyptic scenes behind it in the Caribbean, killing 24 so far.
Richard said early this morning that there 'needs to be an enormous aid effort' after the island was 'decimated', as the British Government's relief effort begins.
He branded Irma "the storm of the century", but also warned about Category 4 Hurricane Jose, which is following in its wake.
The tycoon said: "The boats are piled up like matchsticks in the harbour. Huge cargo ships were thrown out of the water and into rocks. Resorts have been decimated.
"The houses have their roofs blown off; even some churches where people sheltered have lost roofs. But the whole British Virgin Islands community is rallying round."
In a video posted to his Instagram account, his son Sam explains that he has spent a "very long day" organising to fly back to the BVI with supplies.
He shows a pile of suitcases and boxes packed with food and clothing that he is planning to take to the islands - one of which, Necker, is owned by his father - today.
Sam, a photographer, explains: "Going to do my best to help the people on the ground there."
In an appeal to boat owners, he adds: 'Stock them with Tarpaulins, food, water, batteries, torches, clothes, water purification tablets and anything else you think might be useful.
"Going to be harrowing to see my home and so many others beloved place so decimated but will do all I can to get aid to the people that need it most!"
On his blog, meanwhile, dad Richard - who spent the storm in his wine cellar while his island was devastated - said he and his team have been doing 'everything we can to help the community' in the BVI.
He said: 'The wonderful team have been going around to all of our team members on Virgin Gorda to check they are safe and well.
'There is a huge amount of damage to buildings, but fortunately everyone we have seen so far has been ok.
"There needs to be an enormous aid effort. Please get the word out to anyone who can help further. We have Necker Belle coming in from Barbados with food, water and supplies and we hear others are sending boats."
He also said that "man-made climate change is contributing to increasingly strong hurricanes causing unprecedented damage," adding: "The whole world should be scrambling to get on top of the climate change issue before it is too late - for this generation, let alone the generations to come."
Downing Street, meanwhile, said it was waiting for "a full picture of intelligence to come through" of the Caribbean, adding: "Three flights departed [yesterday] morning carrying marines and engineers as part of the MoD task force."
A spokeswoman added: "[Today], another C17 will leave carrying two Puma helicopters.
And the RFA Mounts Bay ship is due to arrive in the British Virgin Islands ... bringing aid and helicopters to help deliver supplies."
The Government explained that the Department for International Development's disaster response centre was sending out supplies of aid to be loaded on to HMS Ocean, which has been diverted from the Mediterranean to head for the Caribbean to help with the disaster relief efforts.
The aid heading for HMS Ocean includes 10,000 buckets and 5,000 solar lanterns, the spokeswoman said.
One resident on the islands said his home has been absolutely destroyed - and with it most of his possessions.
Dan Perkins told MailOnline he was not on the islands when the storm hit, but has been told that about the damage done to his property.
He said: "My house started at the top of the hill and ended up at the bottom of it, so I'm told.
"I now own pretty much what I took with me in my suitcase. I'm sure it will sink in soon, but right now we have to focus on the most important things - people who are missing and hurt."
He added: "It's just stuff at the end of the day."
