Police were acting on a complaint filed by Vadim Chivikok, 27, who said his rented bike had gone missing from his house on Samui Island's popular Chaweng Beach.
After reporting the theft to the police, Mr Chivikof received a phone call from Roman Koval, 37, who told him he had the missing bike and wanted a 15,000 baht ransom for it.
The tourist-turned-thief asked the victim to hand over the money to him at Bor Pud market in tambon Bor Pud of Koh Samui district on Tuesday morning.
Police swooped on him when he turned up to collect the cash from Mr Chivikok. A search of his hotel also uncovered another stolen bike parked behind his rented room.
Mr Koval allegedly confessed to having stolen rented bikes from four other foreign tourists and coerced them into paying money to get them back. He said he committed the thefts because he had spent all of his money during his holiday on the island.