Mary Philbin was born on July 16, 1902, in Chicago, Illinois, into a middle-class Irish American family. She was the only child of John Philbin, an immigrant from Ireland, and Mary Philbin, who was very proud of her daughter. She showed an early interest in acting, often re-enacting plays she saw with her dolls. She was particularly fond of the theater and opera, thanks to her father's influence.

Her beauty and talent were recognized early on, and she won a beauty contest sponsored by Universal Pictures, which led to her signing a contract with the studio. She made her screen debut in 1921 and quickly rose to fame.

Her most celebrated role came in the 1925 silent film "The Phantom of the Opera," where she played Christine Daaé opposite Lon Chaney. Her ethereal presence on screen earned her critical acclaim, and she was referred to as "one of the astonishing anomalies of motion pictures" by Motion Picture Classic.

Throughout the 1920s, she starred in several high-profile films, including "The Man Who Laughs" (1928) and "Drums of Love" (1928). Despite her success, her career declined with the advent of sound films, although she did dub her own voice for the re-release of "The Phantom of the Opera." She retired from acting in 1930 and lived a reclusive life in Huntington Beach, California.

Mary Philbin was in a relationship with Paul Kohner, a film executive, from 1923 to 1927. They were secretly engaged but never married due to disapproval from both families. She spent the remainder of her life quietly, making rare public appearances, including attending a memorial service for Rudolph Valentino in 1988 and the Los Angeles opening of the Andrew Lloyd Webber musical "The Phantom of the Opera" in 1989.

She passed away on May 7, 1993, at the age of 90 from pneumonia.