The project has been discussed in "non-business conversations", according to Bloody Disgusting.
Walking Dead creator Robert Kirkman appeared to rule out a movie version in 2010, saying: "I didn't want to do a movie for obvious reasons, and TV always seemed like a tough sell. But AMC got behind it and pushed the limits."
A third season of the zombie drama is currently filming, with new cast members David Morrissey and Danai Gurira joining Andrew Lincoln, Sarah Wayne Callies and the rest of the show's regular cast in Georgia.
Kirkman has insisted that he is "really proud" of the upcoming episodes, suggesting that they have a "new tone".
The Walking Dead will return to FX in the UK and AMC in the US in October.