Armen began her career writing for TV westerns, including The Rifleman and The Big Valley. She later worked on such shows as Marcus Welby, M.D., Barnaby Jones, and Wonder Woman. She also wrote The Mod Squad episode "A Time of Hyacinths" (1970) in which Warren Stevens had a guest appearance alongside series regular Tige Andrews. Margaret Armen passed away due to heart failure in her home in Woodland Hills, California on 10 November 2003 at the age of 82.