White, the daughter of a scrap merchant, was born in Hammersmith, London, and attended the Corona Stage Academy. She played minor roles in films from 1949 until the late 1950s, when she began to play more substantial supporting roles in films such as Carry on Teacher (1959) and Never Let Go (1960) in which she played the girlfriend of Peter Sellers.

She continued working regularly, and drew attention for her performances in the television version of Nell Dunn's Up the Junction (1965). She followed this success with roles in Cathy Come Home (1966) and the films Poor Cow (1967), based on another Nell Dunn book, and I'll Never Forget What's'isname (1967). Up the Junction, Cathy Come Home and Poor Cow were all directed by Ken Loach.

She achieved a public profile with her performances in the television play Cathy Come Home (1966) and the films Poor Cow (1967) and I'll Never Forget What's'isname (1967), but alcoholism and drug abuse damaged her career, and from the early 1970s she worked infrequently.

White starred opposite Alan Bates, Dirk Bogarde and Ian Holm in the film adaptation of Bernard Malamud's The Fixer (1968) and then travelled to Hollywood in 1968 to make Daddy's Gone A-Hunting (1969). She appeared in a Dean Martin western film, Something Big (1971), and had major roles in Dulcima (1971) and Made (1972), with the singer Roy Harper. During the late 1960s, White was considered one of the most promising actresses in British cinema, but her problems with alcoholism and substance abuse, as well as unhappy relationships with male stars such as Richard Burton, Frank Sinatra, Oliver Reed and Paul Burke, hindered her career. She did, however, have a prominent role as a hostage in The Squeeze (1977).

After living in Hollywood for several years, White returned to London to star in Nell Dunn's play Steaming at the West End's Comedy Theatre, filming Nutcracker at the same time. Despite receiving excellent reviews for Steaming, she often was late, missed performances, and finally was sacked. In 1981, a biography, Carol Comes Home, by Clifford Thurlow, was published. Although White received publicity for the play and the biography, she was not able to renew her career. She returned to the United States, where she lived for the remainder of her life.

White died in 1991 in Florida, at the age of 48. The cause of her death is disputed, with some sources claiming she took a drug overdose and others (including Upton and The Sunday Times) suggesting she succumbed to liver disease. She had two sons from her first marriage.

A television film of her life, The Battersea Bardot, was shown in 1994 with Wendy Morgan as White.