Born in Sherman Oaks, California, Olsen began acting at age four alongside her sisters Mary-Kate and Ashley Olsen. She had her debut film role in the thriller Martha Marcy May Marlene in 2011, for which she received praise. Olsen received a BAFTA Rising Star Award nomination and graduated from New York University two years later.
Outside of her work with Marvel, Olsen starred in the monster film Godzilla (2014), the mystery film Wind River (2017), the dramas Ingrid Goes West (2017) and His Three Daughters (2024), the science fiction thriller The Assessment (2025), and the romantic comedy Eternity (2025). She also starred as a widow in the drama series Sorry for Your Loss (2018–2019) and as Candy Montgomery in the miniseries Love & Death (2023), the latter earning her another Golden Globe Award nomination.