Harris began his comics career in 1989. Initially he flitted from assignment to assignment, and worked on T-shirts and ads to pay the bills during dry spells in his comics work. He rose to prominence in 1994 with the publication of DC comics’ Starman. Summarizing his career up to this point, he remarked “When you jump around as a freelancer, it’s easy to have your attention span dwindle down to that of a gnat. When I got Starman, I had to buckle down and just get serious about the work.”Co-created with James Robinson, Starman led the two to critical acclaim and eventually an Eisner Award for the “Sand and Stars” story arc.
After four and a half years on Starman, Harris left to pursue other projects but remained as cover artist on Starman for another year and a half. During this time he was also one of the original members of Atlanta’s Gaijin Studios.
He pencilled the series Ex Machina with Brian K. Vaughan, published by Wildstorm from 2004 to 2010, and War Heroes with Mark Millar, published by Image Comics, which has only had 3 issues published as of 2013. In April 2010, Following the completion of Ex Machina, Harris announced that he and B. Clay Moore would produce a series called The Further Adventures of the Whistling Skull, this was later turned into JSA Liberty Files: The Whistling Skull, tying it into the earlier JSA Liberty Files stories he did, and the first issue saw print in December 2012.Concurrently with this, he launched a new series with Steve Niles, ‘Chin Music’, set to start in April 2013, then a new creator owned series, Roundeye: For Love.
In the late 1990s he moved on to form Jolly Roger Studio, in Macon, Georgia.
Other works include key frame animation and story boards for Chevrolet commercial, illustration for Cartoon Network, product design and illustration for Universal’s The Mummy.