Norman, a red-footed booby, was nursed back to health by the RSPCA and flown to the Cayman Islands by British Airways on Friday.
It is not known how the seabird reached the south coast of England.
He will join a flock of fellow booby birds at a nature reserve. The RSPCA said he would be home for Christmas.
Captain Shaun Griffiths, who flew BA0253 from the UK to Grand Cayman, said: "Despite having flown a number of VIPs before, Norman is by far the most unusual."
The pilot said beaches on the Cayman Islands were among the most beautiful in the world, adding: "We are thrilled he can start the new year in the sunshine."
Norman was found bedraggled on a pebble beach in St Leonards by a passer-by in September.
Collected by East Sussex Wildlife Rescue Ambulance Service (WRAS), he was found to be underweight and dehydrated.
At the time, WRAS founder Trevor Weeks said the "stunning" bird had been found looking extremely exhausted and just sitting on the beach.
He said as far as he knew, no booby bird had ever been found in the wild in the UK before although one appeared to have visited Spain.
Norman spent three months with the RSPCA being fed sprats - a type of small fish - and cared for under a heat lamp to keep him warm during the drizzle and cold of a British autumn.
The charity said its wildlife workers are more used to dealing with gulls and terns.
Richard Thompson, wildlife rehabilitation team manager at the RSPCA Mallydams Wood centre, said: "We have done everything possible to build his weight up and keep his strength up to prepare him for his long journey home."
Norman will spend 30 days in quarantine before he is released to start his new life next year.
A tropical bird that was found exhausted on a Sussex beach has had an easier journey home - on a 12-hour flight from Heathrow.