Billingsley's stage debut came in Detroit, Michigan, and she debuted on Broadway in the musical Carnival!. Her film debut came as James Caan's girlfriend in the 1964 thriller Lady in a Cage, and appeared in the romantic drama The Young Lovers the same year. She had a recurring role on the daytime soap opera General Hospital and prominent roles in such films as The Spy with My Face (1965), C.C. and Company (1970), Brute Corps (1971), Welcome Home, Soldier Boys (1972), White Lightning (1973), The Thirsty Dead (1974) and Hollywood Man (1976).