Aoki was born in New York City, New York, and grew up in California and London, attending high school at The American School in London. Her Japanese father, Hiroaki "Rocky" Aoki, a former Olympic wrestler, was the founder of the Benihana restaurant chain and owned it until his death on July 10, 2008. Her mother, Pamela Hilburger, is a jewelry designer and a painter of German and English heritage.
Aoki was discovered in New York at a Rancid concert she had gatecrashed. She started modeling when she was 13, the same year Aoki was introduced by her godmother to Kate Moss, who would later take the young model under her wing. She was signed to Storm Model Management at age 14. In 1998, at the age of 16, Aoki replaced Naomi Campbell as the face of Versace.