Martin's first major work in the 1980s was Gnatrat, a parody of Batman featuring a rat who dresses as a gnat to fight crime. He went on to work on the Teenage Mutant Ninja Turtles series, and created a long-running humor strip featured in Comics Buyer Guide, "20 Nude Dancers 20". As an editor, Martin created the anthology Hyena and briefly oversaw a humor section in Heavy Metal. He then moved toward working almost exclusively in children's comics, often for Nickelodeon's Nickelodeon Magazine, while producing other work for his Web site.

His collaborations with long-time friend Jim Woodring include the children's series Tantalizing Stories, and several mini-comics featuring their characters Frank and Montgomery Wart.

Martin is often mistaken for the race-car driver Mark Martin; this is a frequent subject of his comics in recent years.