Chelsea Smith and her brother, actor Wyatt Smith, were born in Lake Arrowhead, California. Chelsea made her first on-screen performance in 2004 with a guest spot on Fox sitcom Oliver Beene (2003) and with a voice work in the TV movie The Mystery of Natalie Wood (2004). Chelsea's break out role on the silver screen was at age 8 in the romantic comedy 40 Yıllık Bekar (2005). Chelsea was cast as Julia, opposite Steve Carell, Catherine Keener and Paul Rudd. Chelsea was also cast in the movie, Duress, and appeared in the film, Ramona and Beezus.

Chelsea is a UCI Graduate in Biological Sciences.