Smith began her career as a teenage model.She moved to Los Angeles and planned on doing commercials to support herself while she attended UCLA. She was in an HBO commercial that aired during the Super Bowl; this exposure led to her finding an agent and beginning her acting career.Her most notable role is Mary Winchester on the paranormal and fantasy TV series, Supernatural.She has also had guest appearances on Rizzoli & Isles, Friends and Criminal Minds. Her film work includes Jerry Maguire and Transformers.