Peyton List was born in Boston, Massachusetts, to Douglas List and wife Sherri Anderson, but grew up in Baltimore, Maryland, with her sister Brittany List. She began her education at Cedarcroft pre-school and Calvert School, and then went to the Roland Park Country School in Baltimore. At the age of eight, she connected with Camera Ready Kids, a children's modeling agency. Her first significant commercial appearance was as one of the "daughters next door" (together with her sister) in Washington Square. She also appeared as a Christmas Caroler in Enemy of the State, also filmed in Baltimore.
Peyton's early modeling successes included television commercials for Kraft Macaroni and Cheese and Little Monkey Lost. At the age of 12, she was invited to attend the School of American Ballet's summer program. Under the tutelage of Ford Kids, Peyton did major campaigns with Limited Too (she appears on the inside cover of Limited Two's IPO), Polo Ralph Lauren, and other advertisers seeking to reach the young teen market. Soon, List was leaving school two or three times a week for modeling assignments. At the age of 15, she signed a three-year contract with As the World Turns playing Lucy Montgomery.