[10] Garner made her film debut at age 17 in Sean Durkin's Martha Marcy May Marlene, playing the role of Sarah.

In 2016, she appeared in an episode of Lena Dunham's HBO comedy series Girls titled "The Panic in Central Park".

Garner continued acting in television and was cast in a recurring role in the third season of the FX period spy-thriller series 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.

[13] Beginning in 2017, Garner starred as Ruth Langmore in the Netflix crime drama series Ozark, opposite Jason Bateman and Laura Linney.

[14] The role gained her critical acclaim and three Primetime Emmy Awards for Outstanding Supporting Actress in a Drama Series.

[21][22] In 2022, Garner was cast in thriller film Apartment 7A which serves as a prequel to 1968's Rosemary's Baby, directed by Natalie Erika James.

[24] In June of the same year, Garner was chosen by Madonna to play her in her self-produced biopic Who's That Girl; the project was put on hold while the singer was touring,[25] and work on it had reportedly restarted in 2024.

[28] In April 2024, Garner was cast as Shalla-Bal / Silver Surfer in the upcoming Marvel Cinematic Universe film, The Fantastic Four: First Steps.