Irène Jacob was born in Paris, France, the youngest child after three brothers. She comes from a highly educated and intellectual family, her father is a physicist, her mother a psychologist, and of her brothers, one is a musician and the other two are scientists.

As an infant, her family moved to Geneva, Switzerland where, as a young girl, she became interested in the arts, making her stage debut at the age of 11. She attended the Geneva Conservatory of Music, earned a degree in languages (she speaks English, German, Italian and French), studied acting in Paris at the prestigious Rue Blanche (the French national drama academy) and at the Dramatic Studio in London, England.

Three years after Jacob's return to Paris, the then 21-year-old drama student obtained her first movie role in the 1987 film Au revoir les enfants followed by several more minor roles until her big break came when Polish director Krzysztof Kieślowski cast her in the lead role of his 1991 motion picture, La Double vie de Véronique. For her performance, Jacob won the Best Actress Award at the Cannes Film Festival.

An introvert by nature, Jacob has the remarkable ability to express the emotional turmoil of her characters with very few words. This was very evident when Kieślowski used her again to star alongside Jean-Louis Trintignant in Three Colors: Red, the third part of his highly acclaimed masterpiece, the Three Colours trilogy. The film, and her performance, gained huge international recognition bringing many offers from major American motion-picture studios. Her highest grossing US picture as of 2004 was U.S. Marshals (released 1997), in which she starred opposite Tommy Lee Jones.

Jacob's film career slowed down in subsequent years, and after a series of independent, mostly European, movies, she revived her theatre career. Her 2000/2001 London West-End performance as the title character in Madame Melville opposite Macaulay Culkin was crucial to that development.