Collins was born in London, England, to Joseph William "Will" Collins (a South African-born Jewish theatrical agent), and Elsa Bessant Collins, a dancer. Jackie is listed as Jewish, on several sites. She has one sister, the actress Joan Collins (b.1933), and a brother Bill Collins (b. 1946). She attended secondary school at the Francis Holland School in central london. However, after what seemed to be a sunny childhood in England, Collins was expelled from high school for poor attendance in 1952. Her parents swiftly sent her to live with her sister Joan Collins, who at the time was starting what would be a roller-coaster career, in Los Angeles. As she later said her parents were fed up with her and no longer felt they could handle her, so they gave her an ultimatum: reform school or Hollywood. "So I went, `I think Im gonna go with Hollywood`".

While living in Hollywood, Collins attempted to start a film career similar to her sisters. On the whole her career proved fruitless with Collins appearing in only a handful of forgettable films.

Disillusioned with her life, Collins left Los Angeles and returned to London where she married her first husband, jet-setter Wallace Austin, in 1955 and they had a daughter, Tracy--but it was not a happy union. Disgusted with her husband`s drug abuse, Collins was not surprised when he abandoned her after only a few years of marriage. She divorced him soon after and went to live with her parents at their flat in north London. He was found dead in a car in Hampshire in 1964, leaving Tracy fatherless. "A tragic marriage", Collins would later recall. "He was really very sick. He was a manic depressive. A fabulous person. But he was put on drugs - methadrine - for the depression".

In 1966 Collins married for the second time to art gallery and Tramp Nightclub owner Oscar Lerman. Together they had two daughters, Tiffany and Rory; additionally, Lerman formally adopted Collins`s daughter Tracy.