Simpkins' first film appearance was in
Sherrybaby, playing a lead role opposite
Maggie Gyllenhaal. She has performed three times alongside brother Ty, in
Pride and Glory,
Revolutionary Road and
Arcadia. She had a lead role as Lizzy Muldoun in the film adaptation of
Wendy Mass's book
Jeremy Fink and the Meaning of Life, written and directed by
Tamar Halpern. In 2021, she played Alice in the
Fear Street trilogy. In 2025, she starred in the music video for the song "Radioactive Dreams", the first single from the
Chat Pile and
Hayden Pedigo collaborative album
In The Earth Again. == Personal life ==