On television, Siu has appeared in the spy thriller Alex Rider (2020–2024) and the BBC drama Everything I Know About Love (2022).

Siu was born on 11 March 1993 and lived in Lamma Island, Hong Kong until she was four years old, before moving to and growing up in Forres in Moray, north-east Scotland.

[7] Her first major movie role came in 2017, when she played Lisa in John McPhail's zombie musical Anna and the Apocalypse, performing the song It's That Time of Year.

Siu was named as one of the 15th Screen International's Stars of Tomorrow 2018 an annual talent showcase that spotlights up-and-coming British and Irish actors, writers, directors and producers from the UK and Ireland.

[11] In 2020, Siu starred as Kyra, a student from Point Blanc, in the IMDb television teen spy series Alex Rider.