In 2013, Brown made her acting debut as a guest star in the ABC fantasy drama series Once Upon a Time in Wonderland, a spin-off of Once Upon a Time, portraying the role of Young Alice. In 2014, she had a starring role in the BBC America paranormal drama-thriller series Intruders as Madison O’Donnell. She then made guest appearances in the CBS police procedural drama NCIS, the ABC sitcom Modern Family, and the ABC medical drama series Grey’s Anatomy.
In 2016, Brown began starring as Eleven in the Netflix science fiction drama series Stranger Things. Her portrayal received critical acclaim and she was nominated for the Screen Actors Guild Award for Outstanding Performance by a Female Actor in a Drama Series and the Primetime Emmy Award for Outstanding Supporting Actress in a Drama Series. She won the Screen Actors Guild Award for Outstanding Performance by an Ensemble in a Drama Series with her co-stars. She will be returning for the second season.
In November 2016, Brown starred in the music video for Sigma and Birdy’s single “Find Me”. Since November 2016, she has appeared in commercial advertisements for Citigroup. In January 2017, she made her modelling debut in Calvin Klein’s By Appointment campaign. The following month, she was signed to the agency IMG Models.
Brown will make her feature film debut in the Godzilla sequel, Godzilla: King of the Monsters.