[1][2] Ramsey also played Mildred Hubble in the 2017 CBBC series The Worst Witch,[3] and starred in the 2022 historical comedy film Catherine Called Birdy.

[8] Ramsey started acting as a hobby at the age of four, through the Loughborough branch of Stagecoach Theatre Arts, which they attended for seven years.

[10][12][13][14] From 2016 to 2019, Ramsey portrayed Lyanna Mormont in the HBO fantasy drama television series Game of Thrones.

After their debut appearance in "The Broken Man" (season 6, episode 7), fans and critics noted Ramsey was a standout actor for portraying their character's no-nonsense leadership style.

[20] Ramsey voiced the title character in the 2018 Netflix original series Hilda, for which they won the 2019 BAFTA award for best "Children's Animation" along with Luke Pearson, Kurt Mueller, and Stephanie Simpson.

[24] In July 2023, they became the first non-binary actor to be nominated for Outstanding Lead Actress in a Drama Series at the 75th Primetime Emmy Awards, for their portrayal in The Last of Us.

[25] In September 2023, Ramsey was included on Time's 100 Next list; actor Emma D'Arcy praised their acting skills and activism.