The illustrator is taking court action against his former collaborator, alleging that he was duped into signing away his rights to the franchise, which spawned the hit television show.
Kirkman, who continues to pen Walking Dead for Image Comics, responded by calling the case "ridiculous". However, Moore has now hit back, accusing the scribe of "deception" as well as "unlawful and immoral" conduct.
He told CBR: "Robert procured our agreement by deception. He then failed to perform the agreement. While he has paid some royalties, he has refused to provide the documents and information he is required to provide under the agreement and which are necessary to confirm that he has paid what is owed.
"I have tried to obtain this information by means other than a lawsuit but have been denied and stonewalled in every attempt by Robert and his sharp-elbowed handlers. His conduct is unlawful and immoral, and he ought to be held accountable.
"He can try to falsely minimise my contributions, but both he and I know the truth, which I believe will be revealed in the course of this lawsuit."
Kirkman's attorney has called the lawsuit "totally frivolous", adding: "Mr. Moore is owed no money at all. And Mr. Moore's contract has an attorneys' fees clause in it, so we will be going after him to collect attorneys' fees."
Moore worked on the first six issues of Walking Dead with Kirkman and provided covers up to issue #24. He was replaced as interior artist by Charlie Adlard from issue #7.