Her father Raymond Legrand was a conductor and composer renowned for hits such as Irma la douce, and her mother was Marcelle Ter-Mikaëlian (sister of conductor Jacques Hélian), who married Legrand in 1929.

Her maternal grandfather was of Armenian descent and considered a member of the bourgeoisie.

Legrand was the original lead soprano of The Swingle Singers and was the vocalist who dubbed the part of Madame Emery in Les parapluies de Cherbourg, the music for which was composed by her brother Michel Legrand.

[citation needed][4] Legrand was the featured soprano on the track "Fires (Which Burn Brightly)" on the 1973 Procol Harum album Grand Hotel.

[5] Her niece Victoria Legrand is a member of the American indie pop group Beach House.