The beauty queen's birth date is sometimes listed as 1922. Jergens first rose to prominence in the late 1930s, when she was named "Miss World's Fairest" at New York's 1939 World's Fair and in the early 1940s, she worked as a Rockette, and was named the Number One Showgirl in New York City.

After a few years of working as a model and chorus girl, including being an understudy to Gypsy Rose Lee, Jergens landed a movie contract with Columbia Pictures in 1944. That's when brunette Jergens became a blonde. Her chorus girl past came in handy when she played an exotic dancer in Armored Car Robbery (1950). She was usually cast as blonde floozies and burlesque dancers. She once played Marilyn Monroe's mother in Ladies of the Chorus (1948) despite the fact that Jergens was only 9 years older than Monroe.

Her only child, actor Tracy Langan, predeceased her.