At an early age she decided to follow a career as an actress and, after being expelled from school in Australia, was schooled in New York while living with her father. She later won a scholarship to the Royal Academy of Dramatic Art (RADA) and moved to Britain in the early 1950s.
With Laurence Harvey in the television play The Small Servant. Both made their US television debuts in this production for The Alcoa Hour (1955).
After graduation, Cilento found work on stage almost immediately and was signed to a five-year contract by Sir Alexander Korda. Her first leading role in a film was in the British film Passage Home (1955), opposite fellow Australian Peter Finch.
In 1985, Cilento married playwright Anthony Shaffer, who wrote the script of The Wicker Man; she met him when she appeared in that film as Miss Rose in 1973, and he joined her when she returned to Queensland in 1975.
Cilento continued working as an actress, in films and television. In the 1980s, she settled in Mossman, north of Cairns, where she built her own outdoor theatre, named "Karnak", in the tropical rainforest. The venture allowed her to participate in experimental drama.
In 2001, she was awarded the Centenary Medal for "distinguished service to the arts, especially theatre".
In 2006, Cilento released her autobiography, My Nine Lives.
In 1975 Shaffer made his home in Queensland with Cilento. They married in 1985. Cilento was Shaffer's third wife; he had two daughters from a previous marriage.
In her 2005 autobiography My Nine Lives, Cilento alleged that Sean Connery had abused her mentally and physically during their relationship; Connery had been quoted as saying that occasionally hitting a woman was "no big deal". In 2006, Connery cancelled an appearance at the Scottish Parliament because of the controversy, and said he had been misquoted and that any abuse of women was unacceptable.
However, there is a video interview with Barbara Walters where Connery said he has not changed his opinion and if it is merited, it's okay to slap a woman.