Rachel Hannah Weisz was born in Westminster, London, England. Her mother, Edith Ruth (née Teich), was a psychotherapist, and her father, George Weisz, was a Hungarian-born mechanical engineer. Her upbringing in a Jewish intellectual household instilled in her a love of learning and the arts, shaping her inquisitive nature and approach to acting.

While studying English at Trinity Hall, Cambridge, Weisz co-founded the theatre troupe Cambridge Talking Tongues, winning the Guardian Student Drama Award at the Edinburgh Fringe Festival for an improvised piece. This marked her entry into the performing arts and provided a foundational experience for her future career. Early TV roles followed, including an appearance in 'Inspector Morse'.