Muller was born in Kentish Town, London, and was raised by parents Matt Müller and Nicola Jackson, who separated when she was six.

[3] Muller first began writing her own music at the age of eight and attended Fine Arts College in Belsize Park, north London.

In 2007, as a child, she appeared in the music video - directed by her aunt, Sophie - for "Grace Kelly" by Mika.

[4][5] While working at American Apparel and in a pub in Kentish Town, Muller began publicly performing.

[13] Alongside the release of "Therapist", Muller also announced her first national tour, visiting five cities across the United Kingdom.

[21][22] On 3 March 2023, Muller released a collaboration with Sigala, Caity Baser and Stefflon Don, titled "Feels This Good".

Muller lists Gwen Stefani, Lily Allen, and Florence and the Machine amongst her musical influences.