The 25-year-old London man, whose name has not been released, was found at an apartment in the central Macerata province on Wednesday night, detectives said.
He was kept handcuffed and barefooted in a room at an address in the town of Monte San Giusto, which is about 106 miles southeast of San Marino.
The man was allegedly kidnapped by a gang of four people, who demanded he pay them €7,000 (£5,918) to be released.
They allowed the victim to call his parents in order to get the money, at which point he used a coded message to signal to them he was being held captive, police said.
The man’s father then contacted the UK's National Crime Agency (NCA), which in turn raised the alarm with authorities in Italy.
Massimiliano Mengasini, a lieutenant colonel at the Macerata unit of Italy’s Ros Carabinieri special operations group, said three men and a woman have been arrested following the alleged kidnap.
“He had been kept in the dark room of an apartment, handcuffed and barefoot,” Mr Mengasini said.
"We are still working to shed light on the case,” he added.
Despite being fed scraps of food for over a week, police said the victim was in a good physical condition but “psychologically tested” by the incident.
Sean Kelly, an operations manager for the NCA’s anti-kidnap and extortion unit (AKEU), said: “We have been working closely with the Italian authorities since the kidnap of a British man was reported.
“NCA officers in Italy and specialists from AKEU, working together with UK policing, have been providing close support to the Carabinieri police as part of its ongoing investigation. We are pleased that this incident has been resolved successfully.”
The victim told police he had been travelling around Italy since June and made visits to several cities including Naples, Sorrento, Florence and Bologna, before arriving in Macerata.
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