Born and raised in South Carolina, Munn spent her childhood taking voice and dance lessons and performing in local theatre productions such as Annie, Oliver, and A Midsummer Night's Dream. Her first professional acting jobs were in productions of Joseph and the Amazing Technicolored Dreamcoat, Grand Hotel, Fiddler on the Roof, and The Pirates of Penzance at various regional theatres across the United States.

Once out of school, Munn knew she wanted to pursue acting full time and moved to New York to study theater. She soon joined the cast of the famous off-Broadway production of The Fantasticks at New York's Sullivan Street Theatre. After starring in more than 500 performances of The Fantasticks in the role of 'Luisa,' as well as in The Wild Party at the prestigious Manhattan Theatre Club, Munn made the move to the west coast. Soon after arriving in Los Angeles, Munn landed the recurring role of 'Caroline,' 'Fez's' (Wilmer Valderrama) overly possessive girlfriend on Fox's That '70s Show. Her other credits include a recurring role on Now and Again and guest starring roles on Law and Order, SVU, JAG, Boston Public, Inside Schwartz, and Charmed. Her film credits include the feature film, White Oleander, starring Michelle Pfiffer and Rene Zellweger.

During a summer hiatus from "What I Like About You", Munn filmed a role opposite Orlando Bloom in writer/director Cameron Crowe's upcoming feature Elizabethtown.

An avid reader and self confessed Internet junkie, Munn enjoys singing, dancing, playing guitar, road trips, and hosting game nights with her friends. She lends her name and support to the non-profit political organization, Rock the Vote, where she is actively involved in encouraging young people to register to vote.