Tom Robinson, 24, hoped to become the youngest person to complete the feat.
He was found sitting on top of his boat with no clothes on, 100 nautical miles south-west off the coast of Vanuatu, a post on his website said.
Local media reports say he was treated for sunburn and dehydration aboard the ship, but is in otherwise good health.
Mr Robinson's record-breaking attempt began when he set off from Peru in July last year. He was hoping to arrive in Cairns, Australia, by December.