She is best known for her work in television series Who Is Erin Carter?, The Midwich Cuckoos, Sherlock and The Missing, as well as feature films A Boy Called Christmas, Radioactive and The Electrical Life of Louis Wain.

[4] She spent three months filming the espionage thriller Deep State in Morocco and Southern England.

[5][circular reference] Watson's first performance in a leading role was in the BFI-funded psychological horror short film Martyrs Lane, written and directed by Ruth Platt.

In April 2019 it was announced that Watson had been cast alongside Jim Broadbent, Sally Hawkins, Kristen Wiig, Toby Jones and Maggie Smith in A Boy Called Christmas, a feature film adaptation of the novel by Matt Haig about the origins of Father Christmas.

In October 2019 she performed on stage with the punk group The Damned at the London Palladium for A Night of a Thousand Vampires.

In November 2019 she appeared as Charlotte Day in BBC drama miniseries Gold Digger with Julia Ormond and Ben Barnes.