Hubert Jopen Reimund, 61, was arrested in November after police raided his hotel room in Phnom Penh and said they found him in bed with the teenager. Reimund, from Cologne, was found guilty at Phnom Penh Court after a brief trial on Thursday, during which the girl testified that he had sexually abused her, prosecutor Sok Kalyan said.
"The court convicted and sentenced him to two years in jail for molesting an underage girl," he told AFP, adding that Reimund denied the charges.
Dozens of foreigners have been jailed for child sex crimes or deported to face trial in their home countries since Cambodia launched an anti-paedophilia push in 2003 in a bid to shake off its reputation as a haven for sex predators.