Born in Paris in 1932, he was the son of Raymond Legrand, an arranger, conductor, and film composer. After his parents' divorce when he was three, Legrand grew up estranged from his father. He showed musical ability at an early age, entered the Paris Conservatory at 11, and graduated at 20 with top honors in composition and as a pianist. He was already a professional musician, having begun performing as a jazz pianist and accompanying singers such as Jacqueline FranÃ§ois at age 15.
Legrand's international career was launched in 1954 when Columbia Records requested a recording of his instrumental music. The result was I Love Paris, an LP of music arranged and conducted by Legrand; it became one of the top-selling popular instrumental albums of the decade. At the end of the 1950s, Legrand began composing for French films, and scored an international hit with his music for Jacques Demy's The Umbrellas of Cherbourg, an experimental but hugely successful film built around sung dialogue. The soundtrack yielded two hit songs, "I Will Wait for You" and "Watch What Happens," and Legrand got Academy Award nominations both for that film and for his score for Demy's follow-up, The Young Girls of Rochefort, in 1967.
He was snatched up by Hollywood immediately after the latter film. His first American score was for an improbable project, the thriller Ice Station Zebra, which with its submarine setting and all-male cast could not have been further removed from the characteristics of the films with which he'd made his reputation. It was a year later, with The Thomas Crown Affair, that Legrand moved to the forefront of popular composers, winning his first Oscar for his work on the film and also generating the song "The Windmills of Your Mind," with lyrics by Alan and Marilyn Bergman, which became a hit in recorded versions by Noel Harrison and Dusty Springfield. A year later, with The Happy Ending, Legrand enjoyed a second hit, "What Are You Doing for the Rest of Your Life."