She was born Joan Schrepfermann in Chicago, where she was also raised. She began her career as a showgirl in Chicago clubs. After appearing as a Dancer in the film The Chicago Kid (1945) and in a part in the television series Have Gun – Will Travel (1958), she moved to California around 1959. In 1959 she reprised the Lauren Bacall role of Sailor Duval in the short-lived television series Bold Venture. During the 1960s, Marshall frequently guest-starred on various television series, including Tales of Wells Fargo, Surfside 6, Hawaiian Eye, and The Jack Benny Program. She also appeared in the films Homicidal (using the stage name "Jean Arless") and Tammy and the Doctor opposite Sandra Dee and Peter Fonda.