Major began his career in 1995 as an employee of FantaCo Enterprises. During that time, he worked the title Blood Letting. Later, he migrated toward Image Comics and Wildstorm Productions, where he worked as a colorist for the James Bond-spoof series Danger Girl, and Stormwatch.
Working at Marvel and DC Comics, Guy worked on the series Uncanny X-Men, the third volume of Green Arrow, the comic book version of the-then TheWB's Smallville, and the fourth volume of Robin. Major's other works include Batmam Beyond Universe, and the seventh volume of Aquaman.