Falciani, who has both French and Italian nationality, was found guilty of industrial espionage by a court in the southern Swiss town of Bellinzona and handed a hefty jail term.
But, as long as he stays in France, he will not serve the sentence.
While working at HSBC's Geneva office in 2008, Falciani made off with material that showed that the bank's Swiss private banking arm helped more than 120,000 clients hide 180.6 billion euros from tax authorities.
Although Falciani has been hailed as a whistleblower, prosecutors accused him of only trying to sell the documents after going to Lebanon with an associate.
After returning to Geneva, where he was questioned and released on condition that he return for a further grilling, he fled to France with his family.
He later handed over an encrypted list of major HSBC clients based in France but dodging its taxes.
HSBC hacked a deal with Swiss prosecutors, paying a penalty of 40 million Swiss francs (36 million euros).