Parrish played Mona Vanderwaal for the duration of the Freeform teen drama series "Pretty Little Liars", based on the book series by Sara Shepard. Mona is introduced in the first season as a teenage outsider who uses her intelligence and resources to torment others anonymously. In March 2012, Parrish was promoted to a series regular for the third season, and stayed a regular for the remainder of the series. For her performance as Mona, she won Choice TV – Villain at the Teen Choice Awards four times from five nominations.