Gilles Jacob confirmed reports that the 35-year-old actress, who won a César award at home as well as an Oscar nomination for her part in the black-and-white movie, will be mistress of ceremonies in the Riviera city on May 16 and 27.
Cannes organisers are to announce the 20-odd films in the official competition at a press conference in Paris on Thursday, with just under a month to go before the world's top movie showcase.
Jacob had planned to announce Bejo's role on Thursday, but Twitter had been abuzz since the French newspaper Le Parisien reported she could host the event.
"This kind of announcement would normally be made by institutions, rather than by agents," he told AFP. "But her smile is sure to win everyone over," he said – insisting he was not upset by the leak.
The French actress – who was born in Argentina and speaks fluent Spanish as well as English – is married to "The Artist" director Michel Hazanavicius, who swept this year's Oscars with five awards including Best Picture.
Bejo owes her international breakthrough to the film.
Recent Cannes ceremony hosts include Kristin Scott Thomas, Monica Bellucci, Diane Kruger and, last year, the French actress Melanie Laurent.