Born in Topango Canyon, California, Starship Troopers was known as a tomboy as a youngster and was the only girl on her Little League baseball team. At 13, she did some modeling and moved into acting after getting a role in MTV's 1994 Rock The Vote campaign in which she played a strung-out supermodel.

TV-movies followed, and as well as her feature debut in Stephen Kay's The Last Time I Committed Suicide, screened at 1997's Sundance Film Festival. After being briefly seen in Paul Verhoeven's big-budget sci-fi actioneer Starship Troopers she had an impressive turn in the vastly different, quirkily independent How to Make the Cruelest Month. In it, she played Dot, the graceful golden girl who seduces the one-time boyfriend of her sister, the troubled protagonist Bell. The by-the-numbers horror film Campfire Tales followed in 1998, along with the topically chilling but clumsily executed internet stalker thriller Dee Snider's StrangeLand, written, produced and starring the titular Twisted Sister frontman as a deranged torturer who meets his victims in web chatrooms. Smart reached her widest audience with a co-starring role opposite James Van Der Beek in Varsity Blues (1999) as a girl who longs for life beyond her small town's high school football-obsessed culture but who, as sister of the injured star quarterback and girlfriend of his idealistic replacement, is tied to it. She was next featured as Shawn Hatosy's upper-class love interest in the poignant 1970s era comedy Outside Providence.

Smart returned to television with a recurring role on the popular college drama Felicity in 1999 and then starred in Road Trip (2000) opposite Breckin Meyer Since then, she has been busy doing feature after feature, including The Battle of Shaker Heights (2003) and Starsky & Hutch (2004), with Ben Stiller and Owen Wilson

Smart has been a spokeswoman for the non-profit group Heal The Bay, an organization that is devoted to cleaning up the Santa Monica Bay, for seven years.