Balfour appeared on the kids TV show Kids Incorporated for one season in 1991. In 1997, he appeared in the pilot for Buffy the Vampire Slayer, as one of the show's very first victims. Years later, Balfour appeared as a dancer in the music video for the song "Fergalicious" by former Kids Incorporated castmate Fergie. He appeared as a regular cast member in three short-lived TV shows. NBC's Hawaii was canceled after seven episodes in 2004, UPN's Sex, Love & Secrets was canceled after four episodes in 2005, and in March 2006, Balfour debuted as Brian Peluso on producer Dick Wolf's short-lived NBC crime drama, Conviction which lasted one season.

He starred in the 2003 remake of The Texas Chainsaw Massacre opposite Jessica Biel. He played a minor character in several episodes of The O.C., as Eddie, Theresa's fiancee, and in the hit HBO show Six Feet Under, as Claire's thuggish boyfriend, Gabriel Dimas during most of the show's first season. In 2005, Balfour starred in the contr