The red-footed booby was discovered in "an exhausted state" on the beach at St Leonards, Sussex, on Sunday afternoon.
The seabird, which is related to the gannet and believed to be a juvenile, was washed ashore with its feathers in a poor state and slightly underweight.
It is currently being cared for at the RSPCA Mallydams Wood centre in Hastings.
More news from Sussex
The bird was rescued by the East Sussex Wildlife Rescue and Ambulance Service (WRAS) following a call from a member of the public.
Founder Trevor Weeks said: "It's an absolutely stunning bird.
"It was looking extremely exhausted, just sitting on the beach.
"Hopefully it will be released back to the wild."
He added: "As far as I can tell, one has never been found in the wild in the UK before.
"From what we gather, one did visit Spain a few years ago, but we can't find many other references to these birds visiting Europe at all."
A bird native to the Galapagos Islands in the South Pacific has been found thousands of miles from home.