Donaldson was born in London, and educated at the Camden School for Girls, living in Kentish Town with her parents. She has a younger sister named Aurelia. She was scouted by Select Model Management in 2003 at the age of 16 while shopping in Camden, and went on to debut in the Fall/Winter 2004 season walking shows for designers such as Chanel, Louis Vuitton, Moschino, Missoni and Jill Sander.
Donaldson has notably landed big campaigns for major fashion houses such as Burberry, Gucci, Versace. and Gap.
As of February 2024, she has amassed 2.2 million followers on her Instagram platform.