Perabo was born in Dallas, Texas and grew up in Toms River, New Jersey, the daughter of Mary Charlotte (née Ulland), a physical therapist, and George William Perabo, a poetry professor at Ocean County College. She is of Portuguese and Norwegian descent. Her parents chose to name her after actress Piper Laurie. Her brothers, Noah and Adam, are also actors. In high school, Perabo appeared in the annual musicals. Her senior year, she was Katie in Meet Me In St. Louis; junior year, Cousin Fan in Mame; sophomore year, Lady Brighton in Me and My Girl; and freshman year, a dancer in How to Succeed in Business Without Really Trying. She was also president of the National Honor Society and the editor of the school literary magazine, Polaris. In 2007, she visited her high school to see How To Succeed In Business Without Really Trying.

She graduated from high school at Toms River High School North and then from Ohio University's Honors Tutorial College in 1998 with a BFA in theater. Aft