Bellows studied in Los Angeles at the American Academy of Dramatic Arts. He made his debut in the film The First Season (1988); in the film drama The Shawshank Redemption (1994 ), he starred opposite Tim Robbins and Morgan Freeman. He received worldwide recognition through the role of Billy Thomas in the television series Ally McBeal, which he played from 1997 to 2002. For this role he was nominated in 2000 to 1998, together with the rest of the ensemble cast for a Screen Actors Guild Award, which he received in 1999, together with, among others, Calista Flockhart, Peter MacNicol and Courtney Thorne - Smith.
In the thriller Judas Kiss ( 1998) Bellows played alongside Emma Thompson. In the thriller Blind Horizon - The Enemy In Me ( 2003) he appeared alongside Val Kilmer.
Bellows is married to actress Rya Kihlstedt since 1994 and has two children.