Moreau studied at the Conservatoire Nationale d'Art Dramatique and became at 20 years of age the youngest member of the Comédie-Française. Le Dernier Amour (1949; The Last Love) marked her film debut, but Ascenseur pour l'échafaud (1957; “Elevator to the Scaffold”; released as Frantic, 1961) and Les Amants (1958; The Lovers) brought her international fame as the embodiment of feminine mystery and sexuality.

Her performances as alienated modern women in Moderato cantabile (1960) and La notte (1961; The Night) and as the volatile, enigmatic Catherine of Jules et Jim (1962) established her as a remarkable actress and compelling screen presence. Her other notable films from the 1960s include Le Journal d'une femme de chambre (1964; Diary of a Chambermaid); Viva Maria! (1965), in which she starred opposite Brigitte Bardot (Bardot, Brigitte); and Campanadas a medianoche (1966; Falstaff, or Chimes at Midnight). She also turned briefly to directing, most notably with L'Adolescente (1979; “The Adolescent”), which starred Simone Signoret (Signoret, Simone).

As Moreau's career continued into the 1980s and '90s, her films, notably Le Miraculé (1987; “The Miracle”) and La Vieille qui marchait dans la mer (1991; The Old Lady Who Walked in the Sea), were well received in France. She starred in such varied roles as a seductive older woman in the BBC movie Clothes in the Wardrobe (1993; U.S. title The Summer House) and as a Jewish grandmother in I Love You, I Love You Not (1996).

By the beginning of the 21st century, Moreau had starred in more than 130 films. Her later movies include Lisa (2001), Le Temps qui reste (2005; Time to Leave), and Plus Tard (2008; Later).