Thorne was born in Pembroke Pines, Florida, to Tamara and Delancey Reinaldo "Rey" Thorne.She has three elder siblings, Kaili, Danielle, and Remy, who are also actors. Her father was of Cuban descent. Thorne has stated that she is also of Italian and Irish ancestry. Thorne's first film appearance was an uncredited role as a sidelines fan in the 2003 film Stuck on You. She has since appeared in film and television projects including Entourage and The O.C. as a younger version of Taylor Townsend.