He told Entertainment Weekly that it is still unclear whether fan favourites from the original comic such as Tyrese and Michonne will appear in the new run.
"We are in the writers' room right now and trying to sketch out a season two plan," he explained. "Anyone who knows how that process works knows that stuff changes day by day. We are in the massive brainstorming phase. We are talking it all out."
However, he claimed that the writing team want past characters Morgan Jones (Lennie James) and his son Duane (Adrian Kali Turner) "both back as soon as possible".
"We're just dying to get [Lennie] back in the show," he said. "He's such a great actor."
Kirkman also confirmed that the villainous Governor will definitely not appear in the second season, but hinted that the character will likely feature in a potential third run.
"[There's] zero percent [chance] in [the] second season," he insisted. "[In the] third season [it's] 92 percent."
The Walking Dead will return to AMC in the US and FX in the UK in late 2011.