Winter was born in Sweden and grew up in London, England; she is fluent in both Swedish and English. Her sole credit as of 2008 is the role of Veruca Salt in the 2005 film Charlie and the Chocolate Factory.

According to the "Different Faces, Different Flavors" documentary, Julia based the modern-day Veruca Salt on the behavior of her younger sister and not on herself, though she also says that she too has an "evil personality". She is also very good friends with fellow Charlie co-star AnnaSophia Robb, even though their characters in the film didn't get along very well.

Julia Winter is the envy of tween-age girls everywhere, having being plucked from obscurity to play Veruca Salt in the 2005 film Charlie and the Chocolate Factory, alongside Johnny Depp. It is the London schoolgirl's first professional role, although she studies drama weekly at a part-time theatre school. When not acting, Julia enjoys horse-riding, tennis, gymnastics, swimming and playing the piano.