Loaded with around 650 personnel and more than 60 tonnes of aid, HMS Ocean, is due to anchor in the waters of the British Virgin Islands later today.
In the coming days, she will deliver aid and equipment where it is needed on the islands.
She is then due to continue to other territories affected by this month’s storms.
Ocean’s arrival means there are now over 2,000 UK military personnel working on the relief effort, making it the largest deployment of UK personnel anywhere in the world.
The Royal Navy ship was dispatched two weeks ago to help with Hurricane Irma recovery efforts.
Britain’s biggest in-service warship was due to take on the role of Flagship to the Standing NATO Maritime Group in the Mediterranean when she was re-tasked to help in the aftermath of the hurricanes.
Commanding Officer of HMS Ocean, Captain Robert Pedre Royal Navy, said: “HMS Ocean stands ready to contribute her significant capabilities to the major UK effort already underway to provide humanitarian assistance and disaster relief to the Caribbean region.
“We bring tonnes of aid, significant air and surface lift capacity and hundreds of highly skilled personnel including engineers, logisticians and medical professionals drawn from all three Services.
“My Ship‘s Company and embarked forces are highly trained and we are ready to make a real difference.”
HMS Ocean stopped in Gibraltar en route to the Caribbean, where she was loaded tonnes of aid, including more than 5,000 hygiene kits, 500,000 water purification tablets and 10,000 buckets.
Brigadier John Ridge, second in command at the UK Joint Task Force, said: “The arrival of HMS Oceanis hugely significant.
“It is really good that we will now be able to bring something to each of those overseas territories and demonstrate that… the UK absolutely supports the overseas territories.”
HMS Ocean will also bring four landing craft into the recovery efforts mix, as well as 10 new 4×4 trucks which have been donated by the government of Gibraltar.
The Plymouth-based vessel, on top of the aid and equipment it is carrying, can produce 300 tonnes of drinking water and generate enough electricity to supply more than 8,000 homes.
Commanding officer Captain Rob Pedre has previously said the ship is “tailor-made” for the humanitarian mission and can “get the aid precisely to where it is needed”.
The helicopters on board include two Chinooks, one Merlin MK2, three Merlin MK3 and three Wildcats.
Defence Secretary, Sir Michael Fallon, said:
“The sight of HMS Ocean dropping anchor in the British Overseas Territories will be welcome respite to those who have seen their islands battered by repeated hurricanes.
“Ocean will help support the longer-term reconstruction of the Caribbean islands which have been devastated by this unprecedented hurricane season.
“The fact that this is our largest operation worldwide underlines the scale of the damage caused and the Government’s commitment to UK citizens spread across the region and in need of our support.”