Roberts was born and raised in Houston, Texas, where he attended Paul Revere Middle School and Robert E. Lee High School. He moved to Sarasota, Florida, where he graduated from Sarasota High School in 1988 and attended Manatee Community College. In 1990, Roberts was accepted to the Juilliard School in New York City, where he graduated in 1994 as a member of the Drama Division's Group 23.
From August 2012 through March 2013, Roberts was in the cast of The Walking Dead as scientist Milton Mamet, who studies "walkers" (zombies). From 2013-15, he played Eliot Delson on Unforgettable.