Aoki was born in New York City, and grew up in California and London, attending highschool at The American School in London. Her Japanese American father, Rocky Aoki, a former Olympic wrestler, was the owner and founder of the Benihana restaurant chain until his death on July 10, 2008. Her mother, Pamela Hilburger, is a jewelry designer 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 Devon under her wing. Moss pushed for Aoki to be signed, and she was signed onto Storm Model Management at age 14.
Aoki has modeled for the fashion houses Lancôme, Chanel, and Versace. Aoki is 5 ft 5 in (1.65 m)— an almost unheard of height for runway models, who are usually at least 5 ft 8 in (1.73 m) height.Aoki has done ad campaigns for Chanel Ready to Wear, Chanel Couture by Karl Lagerfeld, Versace by Steven Meisel, YSL by Juergen Teller, Alessandro Del Aqua, Hugo Boss, Moschino, Ungaro, Fendi, Junko Shimada by Bettina Kimenda and Baby Phat by Kimora Lee Simmons.
Early on in her career Aoki made cameo appearances in several music videos, including Duran Duran's "Electric Barbarella", Primal Scream's "Kowalski" (with Kate Moss), Elton John's "Something About the Way You Look Tonight", Ginuwine's "In Those Jeans" video and, later, in Ludacris' "Act a Fool". Music from this video was featured in the soundtrack of 2 Fast 2 Furious, which Ludacris and Aoki both appeared in. In 2006, she made an appearance in The Killers' video "Bones". Aoki has also made a cameo appearance in the short films accompanying the new Sean Lennon album, Friendly Fire.
Aoki has been on the cover of I-D magazine three times. She was also the face of Lancome cosmetics for four years. Aoki posed for renowned Singaporean photographer Leslie Kee for Kee's 2006 charity photo-book "Super Stars", dedicated to the victims of the 2004 Asian tsunami disaster, which consists of photographs of 300 Asian celebrities by Kee. The same year, Aoki posed for photographer Marc Baptiste’s book Nudes, but she has stated that she was wearing a dress: