Charges of attempted sexual assault and indecent exposure against Conor McGregor have been dropped because of a lack of evidence at a court in the Corsican city of Bastia.
"We had no material evidence to corroborate the complainant's statements, including after the scientific expert input that had been ordered," Bastia prosecutor Arnaud Viornery said.
Mr McGregor's lawyer, Emmanuelle Ramond, said: "We welcome this decision because it is in line with what we expected."
The accusations against the Mixed Martial Arts fighter came when he was on the French island of Corsica last September preparing for a charity 180km water-bike relay race from Calvi to Monaco.
The prosecutor's office in Bastia received a complaint "denouncing acts that could be described as attempted sexual assault and sexual exhibition".
Mr McGregor at the time "vigorously denied any accusation of bad behaviour".
Mr McGregor held the UFC title for featherweights from 2015 to 2016 and lightweights from 2016 to 2018, and also lost to Floyd Mayweather in August 2017 in a lucrative boxing match.
He is due back in action in Las Vegas on 10 July for a third fight against Dustin Poirier.
American Poirier defeated Mr McGregor by knockout during their second meeting in January.
That one-sided bout followed Mr McGregor's first-round knockout victory over Poirier in their first meeting in 2014.