Justin David Smith was born in Marshfield, Wisconsin to Jeff and Tracy Smith, his father being the founder, CEO, and President of a building service contracting firm, and his mother a home worker and member of the board of directors of an unmarried mothers' shelter. He has an older brother, Christopher, whom he greatly admires.
Justin attended Spencer High School, graduating in 2002, and initially pursued a two-year college degree in Criminal Justice with a minor in Psychology. However, after his first semester, he reevaluated his future and switched his major to Music Performance, playing first chair in the College Jazz Band. This experience sparked his interest in acting, and he auditioned for the college play without prior training, unfortunately not securing a role.
The rejection fueled his determination to become a successful actor, and during his last semester, he met aspiring artist Jessica Anderson, with whom he began dating despite Jessica's move to Eau Claire, Wisconsin. They got engaged over the summer, but eventually broke off their relationship, prompting Justin to apply to the prestigious New York Film Academy at the Los Angeles location, where he was accepted.
Justin and his brother Christopher relocated to Studio City, and Justin quickly landed a job as a production assistant on the visual effects stage for the film Idiocracy, starring Luke Wilson. He was hand-picked by Mike Judge to play one of Luke Wilson's "Rodies" in the film. Throughout his schooling, Justin maintained his naturalistic people skills and established connections within the industry.
During this time, he started dating Sonja Long, a third-grade school teacher in Arkansas, and commuted frequently between Los Angeles and Arkansas. After completing his schooling, Justin secured his first Studio Feature Film supporting role in Creepshow 3 as the heroine addict Ronald. Since then, he has appeared in over 30 independent films and, when not acting, works as a Lumberjack and tours with his band Fragile, out of Wisconsin.
Justin and Sonja tied the knot on November 5, 2006.
