Harris began his comics career in 1989 and rose to prominence in 1994 with the publication of DC comics’ Starman. Co-created with James Robinson, Starman led the two to critical acclaim and eventually a Will Eisner comic industry 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.

Current projects include Ex Machina with Brian K. Vaughan, published by Wildstorm and War Heroes with Mark Millar, published by Image Comics. Following the completion of Ex Machina, he starts a new series at Wildstorm The Further Adventures of the Whistling Skull with B. Clay Moore.

In the late 1990s he moved on to form Jolly Roger Studio.

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.

Comics work includes:

• Blade #1 (with Seab Mercer, Buccaneer Publications, 1989)
• A Nightmare on Elm Street (with Andy Mangels, Innovation Publishing, 1991)
• Legion of Superheroes #27 (inks, with Keith Giffen, DC Comics, 1992)
• Nightbreed #18-20 (with Gregory Wright, Epic Comics, 1992)
• The Sandman #56 (inks, with Neil Gaiman, Vertigo, 1993)
• Starman #0-45 (with James Dale Robinson, DC Comics, 1994—2000)
• Doctor Strange
• Batman
• Superman
• The Incredible Hulk
• Spider-Man
• Daredevil
• JLA
• Transmetropolitan
• Robin
• Lazarus 5 (2000)
• Obergeist (2001)
• JSA (2003)
• Green Lantern
• X-Men
• Planetary
• Sabertooth
• Springheel Jack
• Faust
• Reanimator
• Werewolf
• Vampire the Masquerade
• Ex Machina (with Brian K. Vaughan, Wildstorm, 2004—2010)
• With Great Power (with David Lapham, Marvel Comics, 2008)
• War Heroes (with Mark Millar, Image Comics, 2008—present)
• The Further Adventures of the Whistling Skull with B. Clay Moore, Wildstorm, 2010 forthcoming)