She played the lead role of Sophie in Disney's live-action adaptation of The BFG, directed by Steven Spielberg, in 2016.

She lives with her parents and younger sister in Cheshire, and she is a member of the local youth theatre.

[3] In 2024, it was confirmed that Barnhill would voice Aurora in the English dub of Studio Ponoc's The Imaginary.

[4] Prior to this announcement, Barnhill's acting career seemed to be on hiatus as she had not been in anything since 2019's Princess Emmy, in which she voiced the title character.

Back in 2016, Barnhill said in an interview that she was being careful not to let her instant fame go to her head.