Crosby was born in Los Angeles, California. Her father, Lou Crosby, was a scriptwriter-songwriter, and her mother, Linda Hayes, was "an RKO contract Actress in the 1940s". Cathy Lee was the middle daughter of three. Her family is not related to Bing Crosby. Her parents eventually separated, and her father relocated to Australia.
Crosby was a professional tennis player who played at Wimbledon twice, quitting the sport professionally sometime between 1967 and 1970.
As an Actress, her first TV appearance was as Susan in the episode 'The Lay of the Land' in the first season of It Takes a Thief (1968). Her first movie role was as Kay Butler in the 20th Century Fox crime drama The Laughing Policeman (1973) starring Walter Matthau, Bruce Dern, and Louis Gossett, Jr.
In 1974, she starred as the title character in the television film Wonder Woman, a year before Lynda Carter would popularize the role in the weekly series Wonder Woman. Crosby starred in the movie Trackdown (1976) with James Mitchum, and in Coach (1978) with Michael Biehn, in which she played the coach of a high school basketball team who falls for one of her players. She starred in the horror movie The Dark (1979), opposite william Devane, and appeared in the 1982 TV miniseries World War III, with Rock Hudson and David Soul.
Crosby was married at age 21 but divorced within two years. She was in a relationship with football star Joe Theismann throughout the early 1980s. Their romantic relationship ended in 1991, after which she sued him for $4.5 million because he "abandoned his promise to financially support her." Theismann responded with a countersuit, ultimately leading to both settling out of court. According to her autobiography, Let the Magic Begin, when Theismann sued for half of her assets, Crosby declared bankruptcy to stop his litigation, although these allegations have not been confirmed by other sources and the lawsuit documents were kept confidential.
Crosby starred in the Lifetime movie Untamed Love (1994), based on Torey Hayden's One Child, and appeared in the film Ablaze (2001), opposite Ice-T and Tom Arnold.
