Gertrude was born in Philadelphia to William Selby and Olga Hansen, and she was educated in New York City.

[1] She began her career as a vaudevillian before breaking into the nascent motion picture industry around 1914, working frequently on L-KO comedies.

[2][1][3] In 1919, at age 24, she married wealthy Chicago socialite Townsend Netcher in Beverly Hills, California after a three-week courtship, against the wishes of Necher's family.

Selby appears to have retired from acting around the time she married Netcher, and spent several years post-divorce living in Spain with her mother and sister.

[9] Selby then spent time in a penthouse in Paris before returning to the United States in the early 1940s at the outbreak of World War II.