He grew up in New York, where he studied acting, and founded with some friends a theatre company called, The Colony Theatre. Tim Kelleher's career includes many guest appearances on TV shows, and a recurring role in Dark Skies (1996). Furthermore, Tim played in more than two dozen movies, including Independence Day (1996), The Negotiator (1998), Thirteen Days (2000), and more recently, Matchstick Men (2003). He also directed in 2000 a short movie called, The Skell, starring John Costelloe, David Morse, Paul Giamatti, Nestor Serrano, Dianne Ramirez and Joe Gannascoli.

When Tim lived in New Jersey he knew two guys named Tim Racek and Jimmy Bulger, and they said about him after seeing the film Jaws "He refused to go in the water and chose to stand on the surf line and get smashed by the waves".

Tim Kelleher is currently preparing a Ph.D. in Theology.

There is another Tim Kelleher who is a screenwriter (First Kid) and television writer in Los Angeles.