Ms. Christie was born in Assam, India, to Rosemary Ramsden and Frank St. John Christie (an operator of an Indian-based tea plantation). She studied at a convent in India (from which she was expelled) and later at the Central School of Speech and Drama before getting her big break in 1961 in a science fiction series on BBC television, entitled A for Andromeda. The full recordings have now been lost, although the sixth episode and a section of material from the seventh do survive.

Her first major film role was opposite Tom Courtenay in Billy Liar (1963). She played Lara in Doctor Zhivago (1965) and as Bathsheba in Far from the Madding Crowd (1967). Christie was a leading figure in the glamorous London of the 1960s, and continues to make movies including those in the French language with Sophie Marceau in 2001's Belphégor - Le fantôme du Louvre.

During the 1970s she moved to Hollywood and over several years had a high profile relationship with Warren Beatty though following the end of the relationship she returned to Europe.

Christie has never married and has made it clear that she has no plans to do so. Her long-time partner is "The Guardian" journalist Duncan Campbell, which prompted her reluctant return to Los Angeles, California, as that is where he has been based.