In 1997, Timothy returned to his birthplace of Vietnam and co-produced THREE SEASONS, starring Harvey Keitel. A triple award winner at the 1999 Sundance Film Festival. It is the first film to win both the Grand Jury and the Audience Award in festival history as well as the Cinematography Award. In 2000, Bui made his directorial debut with GREEN DRAGON starring Patrick Swayze and Forest Whitaker, who also served as executive producer. The film made its world premiere at the 2001 Sundance Film Festival in Dramatic Competition. It is the recipient of the 2001 Humanitas Prize Award, and the 2001 Austin Film Festival Audience Award. It was theatrically released in 2002. In 2004, he produced INSIDE OUT, starring Kate Walsh, Eriq La Salle, Steven Webber and Russell Wong. Anchor Bay Entertainment released the film in 2006. In 2008, Bui executive produced OWL AND THE SPARROW, an award winning film shot in Vietnam and distributed by Wave Releasing, a distribution company co-founded with fellow filmmakers, Ham Tran and Stephane Gauger. In 2009 he has completed his second feature as director and producer, POWDER BLUE, a character-driven drama starring Forest Whitaker, Jessica Biel, and Ray Liotta and is being distributed by Image Entertainment. He is attached to direct LIGHT OF FALLING STARS for Greenestreet Films.

When he is not making films, he teaches for Freshi Films, a non-profit organization dedicated to bridging cultural differences through filmmaking for inner city kids.