Garrn was born in Hamburg, Germany. Her father works for an oil refinery and her mother is a businesswoman. She has an older brother, Niklas, who is also a model. When Garrn was two years old, she moved with her family to London, and later to Athens when she was six, where she studied at Campion School (Athens). By the age of 10, she moved back to Hamburg with her family. Garrn can play classical piano, having taken lessons since age 6.