I started doing student films at Columbia grad school, and this one student filmmaker, his girlfriend was interning at an open casting call for Susan Shopmaker. Later on, she did the stage reading for Martha Marcy May Marlene, then she cast it, and that was my first movie.
In 2012, Director David Chase invited her to play a small role which he wrote specifically for her in his movie Not Fade Away. Her first starring role was in the 2012 movie, Electrick Children. In 2013, she starred alongside Ashley Bell in the horror film The Last Exorcism Part II, and played the lead in the American remake of the Mexican horror film We Are What We Are.
Garner co-starred in Sin City: A Dame to Kill For (2014) as new character Marcy, a young stripper who crosses paths with another new character, Johnny (Joseph Gordon-Levitt). This marked the first time she acted against a green screen.
In 2015, Garner had a recurring role on the third season of FX's The Americans.
She was to have made her off-Broadway debut in Noah Haidle's play Smokefall at MCC Theater in 2016, but had to drop out during rehearsals because of scheduling conflicts.
In 2017, she appeared in the Netflix series Ozark as Ruth Langmore opposite Jason Bateman and Laura Linney.
