Her career began accidentally in 1959 when she replaced her sister at the last minute in a French radio talent contest Naissance d'une étoile (birth of a star) and won. Director Louis Malle then cast the young starlet in the film he was shooting at the time, Liberté, a project he finally abandoned, making Laforêt's first appearance on screen opposite actor Alain Delon in René Clément's 1960 drama Plein Soleil.
After this film she became very popular and interpreted many roles in the 1960s. She married director Jean-Gabriel Albicocco, who cast her in some of his own works, including La Fille aux Yeux d'Or (The Girl with the Golden Eyes), based on the Balzac story, which would become her nickname.
In her second film, Saint Tropez Blues, accompanied by a young Jacques Higelin at the guitar, she sang the title song and immediately started releasing singles, her first hit being 1963's Les Vendanges de l'Amour. Her songs offered a more mature, poetic, tender alternative to the light, teenage yé-yé tunes charting in France at the time. Her melodies borrowed more from exotic folk music, especially South American and Eastern European, than from contemporary American and British pop acts. Laforêt worked with many important French composers, musicians and lyricists, such as André Popp and Pierre Cour, who provided her with a panoply of colorful, sophisticated orchestral arrangements, featuring dozens of musical instruments and creating a variety of sounds, sometimes almost Medieval,Renaissance or Baroque, other times quite modern and innovative.
At the end of the 1960s, Marie had become a rather distinctive figure in the French pop scene. Her music stood out, perhaps too much for her new label CBS Records, which expected of her more upbeat, simpler songs. She was interested in making more personal records, but finally gave in. Although her most financially successful singles (Viens, Viens, a cover of a British hit, and Il a neigé sur Yesterday, a ballad about the break-up of the Beatles) were released in the 1970s, Marie progressively lost interest in her singing career, moving toGeneva, Switzerland in 1978, where she opened an art gallery and abandoned music more or less altogether.