Daniel Richard Leeming Jones, 31, from Harlow in Essex, was found guilty of breaking pornography laws.
Jones was sentenced at Siem Reap Provincial Court to one month and 22 days in prison which has already been served.
He was one of 10 tourists arrested in January at the ‘Let’s Get Wet’ event in Siem Reap, a popular hub for tourists near Cambodia’s famous Angkor Wat temple ruins.
Authorities previously dropped charges against the nine other travellers and they were ordered to leave the country.
Around 30 officers raided the pool party at a private villa and initially accused the group of “pornographic dancing” and violating local standards of decency.
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The four other Britons originally detained along with Mr Jones were Vincent Harley Robert Hook, 25, Thomas Alexander Jeffries, 22, Billy Stevens, 21, and Paul Francis Harris, 32.