He told Entertainment Weekly that the second run of the AMC zombie drama will be "twice... or three times as good".
"Everyone here is mindful of how well received the first season was," he admitted. "We're breaking our backs, story-wise, to make sure the next season is [better], with a lot of twists and turns."
He insisted that future episodes will keep on "pushing the envelope of what you can do on TV".
"We've been talking to [make-up artist] Greg Nicotero a lot about some cool zombie sutff he has planned," he said. "As much as this show pushed the envelope of gore on TV... all I can say is [that] you haven't seen anything yet."
Kirkman also confirmed that the new run will continue to explore the strained relationship between Rick (Andrew Lincoln) and Shane (Jon Bernthal).
"That's definitely the core dynamic that's going on," he said. "But there's a lot of other interesting stuff in the mix. We're going to be seeing a lot of Andrea (Laurie Holden) and a lot more of Lori (Sarah Wayne Callies)."
The Walking Dead will return to AMC in October.