After receiving his degree, McCoy landed a job as art director/editorial cartoonist for the Belleville News-Democrat in his hometown of Belleville, Illinois. He also began working for Playboy as a gag cartoonist in 1992, and in 1993 "The Duplex" was picked up by Universal Press Syndicate. At this time, the Belleville News-Democrat named him its full-time editorial cartoonist.
In 1990, he won a national cartooning contest sponsored by a newspaper syndicate and USA Weekend. Since then, his editorial cartoons have appeared in The New York Times, USA Today, the international edition of Newsweek and other periodicals.
The National Cartoonists Society named McCoy "Magazine Cartoonist of the Year" in 1996; in 1997, the organization named him "Editorial Cartoonist of the Year." Compilation books of McCoy's editorial cartoons have been published, along with and one book of his "Duplex" strips.
Glenn McCoy is currently art director and editorial cartoonist for the Belleville News-Democrat. His hobbies are all legal. He enjoys long, romantic walks on the beach (preferably not alone), and he plays 12 instruments, although not musically. He sometimes cannot help but feel he is a man with an outy belly button trapped in the body of a man with an inny belly button.