In 1921, shortly after his birth, Montand's family left Italy for France. (When they applied for French citizenship, his father pretended that they left Italy in order to escape Mussolini's regime, but Mussolini came to power in 1922.) Montand came to grow up in Marseille, where as a young man he worked in his sister's barber shop, and later on the docks. He began a career in show business as a music-hall singer. In 1944 he was discovered by Edith Piaf in Paris and she made him part of her act, becoming his mentor and lover.

He went on to international recognition, starring in numerous films. In 1951 he married the actress Simone Signoret, and they co-starred in several films throughout their careers. The marriage was, by all accounts, fairly harmonious, lasting until her death in 1985, although Montand had a number of well-publicised affairs, notably with Marilyn Monroe, with whom he starred in one of her last films, Let's make Love.

During his career, Montand acted in a number of American motion pictures as well as on Broadway. He was nominated for a Cesar Award for "Best Actor" in 1980 for "I comme I care" and again in 1984 for "Garçon!"

In 1986, after his international box-office draw power had fallen off considerably, the 65-year-old Montand gave one of his most memorable performances, as the scheming uncle in the two-part film: Jean de Florette, co-starring Gérard Depardieu, and Manon des Sources, co-starring Emmanuelle Béart. The film was a world-wide critical hit and raised Montand's profile in the US, where he made an appearance on "Late Night with David Letterman".

Montand's only child, Valentin, his son by his assistant Carole Amiel, was born in 1988. In a paternity suit that rocked France, another woman accused Montand of being the father of her daughter and went to court to obtain a DNA sample from him. Montand refused, but the woman persisted after his death. In a court ruling that made international headlines, the woman won the right to have Montand exhumed and a sample taken. It subsequently showed that he was not the girl's father.

In his later years he maintained a home in Provence until his death. He is buried in the Père Lachaise Cemetery, Paris, France.