Amanda Peet was born in New York City, the daughter of Penny (née Levy);, a social worker, and Charles Peet, a corporate lawyer. The two are now divorced. Her father is a Quaker and her mother is Jewish. She has one older sister, who is a doctor. Peet attended Friends Seminary, then studied history at and graduated from Columbia University, where she auditioned for acting teacher Uta Hagen and decided to become an actress after taking Hagen's class.`5` During her four-year period of study with Hagen, Peet appeared in the off-Broadway revival of Clifford Odets's Awake and Sing.

Peet's first screen performance was a television commercial for Skittles. Her early roles included a guest role on the television series Law & Order. She made her film debut in Animal Room (1995);. Peet maintained a steady acting career in relatively obscure indie movies.