The Night of the Living Dead filmmaker revealed that the comic will not include any of the publisher's superheroes, but promised it will feature the undead.
"I'm writing it now, but its plot is a secret," he told Twitch. "It won't involve any of their on-going characters, there will be no superheroes. But it will involve zombies."
Romero, 72, is credited with popularising the zombie sub-genre with his original Dead trilogy, which includes the acclaimed classic Dawn of the Dead.
Marvel has published several zombie titles in the past, notably the Marvel Zombies series - a post apocalyptic take on the Marvel Universe featuring undead versions of its superheroes.
Romero has dabbled in comics before, penning Toe Tags for DC Comics based on an unused movie script.