Kershaw was born in Melbourne. She is the daughter of Kerry, a Psychologist, and Kim Kershaw, who played in the Victorian Football League for Richmond and Hawthorn. She has said that as a child, she was "always in the hospital." At age four, she suffered from meningitis and had to have two spinal taps. She also had a tumour on the knee, and several broken bones from climbing trees. She grew up in Kensington and attended St Michael's Catholic Primary school in North Melbourne. She has stated that she "grew up with 42 nationalities", explaining that her primary school of 150 children was very multicultural. She then attended the Academy of Mary Immaculate in Fitzroy. She later went on to win the Australian 2004 Girlfriend Model Search. She once worked at McDonald's. After high school, in 2005, she moved from Melbourne to Sydney to begin modelling. She lived 100 metres from the beach and it was while at the beach where she was scouted by Chic Management's Kathy Ward, the model scout that also discovered Miranda Kerr and Samantha Harris. She signed with Chic Management within weeks.