Mireille was born to French-born Monique, a French and Spanish teacher, and American Jon on September 22,1975 in Kansas City, Missouri. She has 4 siblings. Mireille was named after a friend of Monique’s. Mireille means admiration or full of wonder.

Mireille went to Houston’s High School for the Performing and Visual Arts. During her senior year, for her role as Anne Frank, Mireille received the first-place scholarship award in the Musicfest Theater Art competition.

In 1994, she made her acting debut, in the TV Movie Without Consent.

Mireille went Brigham Young University. At BYU, she won the prestigious Irene Ryan award where she studied theater.

After BYU, she moved to New York and was in a play by BYU friend Roger Benington, a director. Mireille also was a waitress at a French restaurant, Le Singe Vert.

In, 1999, Mireille appeared in a one-line role in Sex and the City. This part earned Mireille her SAG card.  She then a year later earned her big break when as an understudy in the play The Time of The Cuckoo had to perform without much notice as regular actress forgot a Wednesday matinee.

Eventually, Mireille got the sole female role in the Invention of Love. She also became appearing on TV with a guest roles.

In 2002, Mireille appeared in Shakespeare Theatre Company production of The Winter’s Tale at the Lansburgh Theater in Washington, DC where she played Perdita.

In 2005, she appeared as Honey in Edward Albee’s “Who’s Afraid of Virginia Woolf?” and was nominated for a Tony Award. The play then went to London’s West End.  She also met Alan Ruck when they appeared in a Broadway comedy Absurd Person Singular together and they eventually married in 2008.

Mireille then moved to Los Angeles. She then received the dual role of Kathy and JoDean Marquart in Big Love.

Casting directors on The Killing liked Mireille’s performance on Big Love so much that they casted her as Sarah Linden in 2010.  Enos received nominations for an Primetime Emmy Award for Outstanding Lead Actress in a Drama Series, Golden Globe Award for Best Actress – Television Series Drama, and three Saturn Award for Best Actress on Television for her role of Sarah. The series ended after four seasons in 2014.

Also in 2010, Mireille became a mother when Vesper Vivianne Ruck was born.

In 2013, She played Karin Lane, the wife of Brad Pitt’s character in World War Z. She also played Josh Brolin’s in Gangster Squad and and appeared opposite Reese Witherspoon in the crime drama Devil’s Knot, based on a true story, the West Memphis Three.

In 2014, she appeared in the crime thriller Sabotage directed by David Ayer and later starred in drama film If I Stay directed by R. J. Cutler, based on the novel of the same name by Gayle Forman. Enos co-starred later that year alongside Ryan Reynolds in The Captive, directed by Atom Egoyan.

Enos was cast as lead actress in the thriller Never Here, which was directed by Camille Thoman.

In March 2015, it was announced that Enos had been cast as the lead character in the ABC legal drama series, The Catch, produced by Shonda Rhimes. She plays the lead character Alice Vaughan, the head of a very high-end private detective agency in this “humorous” thriller, which aired its first 10-episode season in spring 2016, and a second season of 10 episodes in 2017 as part of ABC’s “TGIT” Thursday-night lineup.

Also in March 2015, it was announced Enos would star alongside Olivia Cooke in Katie Says Goodbye, an independent film. That same year, she starred in Behold My Heart, directed by Joshua Leonard.

In 2019, she appears as Marissa Wiegler, a role originated by Cate Blanchett in action drama streaming television series Hanna, based on the 2011 film of the same name, on Amazon Prime Video.

In August 2020, it was announced the 2018 film The Lie (her reunion with The Killing’s Veena Sud) would be included in Amazon Prime Video’s Welcome to the Blumhouse horror film anthology. It was released in the anthology’s first installment on October 6, 2020.