Binoche was born in Paris, the daughter of Jean-Marie Binoche, a director, actor, and sculptor, and Monique Yvette Stalens (born 1939), a teacher, director, and actress. Her father, who is French, also has one eighth Portuguese-Brazilian ancestry; he was raised partly in Morocco by his French-born parents. Her mother was born in Częstochowa, Poland. Binoche's maternal grandfather, Andre Stalens, was born in Poland, of Belgian (Walloon) and French descent, and Binoche's maternal grandmother, Julia Helena Młynarczyk, was of Polish origin. Both of them were actors who were born in Częstochowa; the German Nazi occupiers imprisoned them at Auschwitz as intellectuals.
Her great-uncle was Léon Binoche, who won a gold medal in rugby at the 1900 Paris Olympics.
When Binoche's parents divorced in 1968, four-year-old Juliette and her sister Marion were sent to a provincial boarding school. During their teens, the Binoche sisters spent their school holidays with their maternal grandmother, not seeing their parents for months at a time. Binoche has stated that this perceived parental abandonment had a profound effect on her.
She was not particularly academic and in her teenage years began acting at school in amateur stage productions. At seventeen, she directed and starred in a student production of the Eugène Ionesco play, Exit the King. She studied acting at the Conservatoire National Supérieur d'Art Dramatique (CNSAD), but quit after a short time as she disliked the curriculum. In the early 1980s, she found an agent through a friend and joined a theater troupe, touring France, Belgium and Switzerland under the pseudonym "Juliette Adrienne". Around this time, she began lessons with acting coach Vera Gregh.
Her first professional screen experience came as an extra in the three-part TF1 television series Dorothée, danseuse de corde (1983) directed by Jacques Fansten, followed by a similarly small role in the provincial television film Fort bloque directed by Pierrick Guinnard. After this, Binoche secured her first feature-film appearance with a minor role in Pascal Kané's Liberty Belle (1983). Her role required just two days on-set, but was enough to inspire Binoche to pursue a career in film.
