Mireille Enos was born in Kansas City, Missouri, to Monique, a teacher, and Jon Goree Enos. Her Texas-born American father and French mother met while her father was serving on a Mission for the Church of Jesus Christ of Latter Day Saints. She grew up in Houston, Texas, where she attended The High School for the Performing and Visual Arts. She went to Brigham Young University. She spent ten years in New York City, during which time she was nominated for a Tony Award for her portrayal of Honey in Edward Albee's "Who's Afraid of Virginia Woolf?".
She is married to actor Alan Ruck.