She was born Randy Goldfield in Dumont, New Jersey, but changed her name to Justine Goldfield and later to Justine Rendal. She took up writing following a divorce in which she said her husband got almost everything (including her Jaguar and the country house). A graduate of New York University, she was a partner at the management consultants Booz & Company in New York prior to becoming a writer.
Many of her books can be described as revenge fantasies; a constant theme is the mistreatment of women by the men they love, but with the women coming out the winners in the end.
Controversially, in late 1996 Goldsmith said, in response to an Entertainment Weekly reporter's question, that her favorite event of 1996 was when Bob Dole fell off a stage during a campaign function.
She also wrote several books for children, which were published under the name "Justine Rendal."
Goldsmith died as a result of complications from cosmetic surgery. Her final two books were published posthumously.