Clément studied architecture at the École des Beaux-Arts where he developed an interest in filmmaking. In 1936, he directed his first film, a 20-minute short written by and featuring Jacques Tati. Clément spent the latter part of the 1930s making documentaries in parts of the Middle East and Africa. In 1937, he and archaeologist Jules Barthou were in Yemen making preparations to film a documentary, the first ever of that country and one that includes the only known film image of Imam Yahya.

Almost ten years passed before Clément directed a feature but his French Resistance film, La Bataille du rail (1945), gained much critical and commercial success. From there Clément became one of his country's most successful and respected Directors, garnering numerous awards including two films that won the Academy Award for Best Foreign Language Film, the first in 1950 for The Walls of Malapaga (Au-delà des grilles) and the second time two years later for Forbidden Games (Jeux interdits). Clément had international success with several films but his star-studded 1966 epic Is Paris Burning?, written by Gore Vidal and Francis Ford Coppola and produced by Paul Graetz was a costly box office failure.

Clément's second wife was Irish-born Screenwriter Johanna Harwood whom he had met on the set of his 1954 film Monsieur Ripois.

In 1973 he was a member of the jury at the 8th Moscow International Film Festival.

Clément continued to make a few films until his retirement in 1975, including an international success with Rider on the Rain that starred Charles Bronson and Marlène Jobert. In 1984 the French motion picture industry honored his lifetime contribution to film with a special César Award.

Clément died in 1996 and was buried in the local cemetery in Menton on the French Riviera where he had spent his years in retirement.