Grace Of Monaco, which stars Tim Roth as her husband, Prince Rainier of Monaco, kicks off the annual film industry bash in the south of France this May.
Kelly married Prince Rainier a year after meeting him at the festival in 1955, but the film concentrates on her life after her wedding.
The plot revolves around the dilemma she faced after she retired from acting when her old collaborator, Alfred Hitchcock, offered her a part in his film Marnie.
The cast also includes Sir Derek Jacobi, Frank Langella and Parker Posey.
Director Olivier Dahan's previous films include La Vie En Rose, which won Marion Cotillard the Oscar for Best Actress in 2008.
Kidman was on the festival's jury last year which decides which film wins the coveted Palme d'Or award.
The film was originally given a release date for last year but that was put back to March, amid rumours of behind-the-scenes clashes between the director and studio, before being cancelled again.
A festival spokesman said it will "be released on the opening day of the Festival, Wednesday 14 May, in France and in several cities around the world".