Jordan Jacobs from Wiltshire had last been seen in a restaurant at Ko Phi Phi Don last Saturday.
He was reported missing to the Foreign Office by his family, who had become increasingly concerned for his welfare.
Thai police told the BBC that the 21-year-old had been found on a beach on the island.
A spokesman reportedly said: "He was walking around, looking for a diving centre either to apply for a job or do a course.
"We took him to the police station and contacted the embassy and explained everything. He is fine and healthy."
He said he had been without internet access for several days, and was planning to have his visa extended.
The Foreign Office has confirmed it was offering consular assistance to Mr Jacobs’ family.
Jacobs has since posted on his Facebook page: "I’m fine my parents are just over reacting because I said I’m not coming home... and haven’t had internet for a long time stop worrying."
'Missing' British backpacker found alive and safe on Thai island
Register for free to continue reading
Get unlimited access to the latest travel industry news and analysis, comment on articles and sign up to newsletters.
Register for free
Already registered? Login here or below.
Having difficulty logging in? Try these tips, or contact support@flymy.co.uk