Silverstone was born in San Francisco, California, the daughter of Deirdre "Didi" (née Radford), a Scotland-born former flight attendant who worked for Pan Am, and Monty Silverstone, an England-born real-estate investor. Silverstone was raised in a "traditional Jewish household"; her father, a native of East London, is Jewish, and her mother converted to Conservative Judaism before marriage. Silverstone is the youngest of three children and also has a half-sister, London-based rock singer Kezi Silverstone, and a half-brother, David Silverstone, both from her father's previous marriage. Silverstone attended Crocker Middle School, then San Mateo High School but did not complete her high school studies. Silverstone visited England during a summer during her childhood. When she was six, she began modeling and was subsequently cast in television commercials, the first being for Domino's Pizza. She acquired some early modeling and advertising work and was eventually cast as the 'dream girl' on The Wonder Years.
