Jean Acker was born in 1893 on a farm in Trenton, NJ, and was named Harriet. Her father was part Cherokee and her mother was Irish, and they had separated when she was young. Jean attended school at St. Mary's Seminary in Springfield, NJ. Her acting career began in vaudeville and stock-company drama before she moved in front of the cameras.
In 1919 she came to California and negotiated a $200-a-week contract with a movie studio based on the strength of her relationship with her lover, the famed star Alla Nazimova. Within a few months she started another relationship with a younger, less established actress, Grace Darmond. In the midst of this love triangle she met the struggling actor Rudolph Valentino at a party, and they became friends. After a two-month courtship, he asked her to marry him and she accepted. On November 6, 1919, they married, and on their wedding night she locked him out. She wept, claiming she made a mistake and later departed to Grace Darmond's apartment. Valentino tried to reconcile with her but to no avail, and the marriage ended in divorce two years later when Valentino was a major star and Acker's star was waning.
Newspapers had a field day when Valentino was charged with bigamy, as he hadn't waited long enough to marry his second wife, talented set and costume designer Natacha Rambova. Acker sued for the legal right to call herself "Mrs. Rudolph Valentino," and Valentino remained angry at her for several years. However, they rekindled their friendship a few months before his death in 1926. She was one of the last people who saw him alive, and she attended his funeral with her mother. Soon after he died, she wrote and published a popular song about him, "We Will Meet at the End of the Trail."
She played bit parts in films, usually uncredited, until the early 1950s. She and her companion Chloe Carter owned a Beverly Hills building where Patricia Neal lived for several years. She died in 1978 at the age of 85. She and her companion Carter are now buried side by side in Holy Cross Cemetery, Los Angeles, California.