The Paramount and Skydance produced project already has a director in Juan Antonio Bayona ('The Impossible'), who came on board in December and will work closely with Knight on the script, according to the Hollywood Reporter.
'Z', based on the novel by Max Brooks, was one of the summer's surprise hits, grossing USD 202 million domestically and USD 540 million worldwide.
It starred Pitt (who also was a producer via his Plan B shingle) as a United Nations employee who travels the world as he tries to stop a zombie plague, all the while trying to communicate with his family.
Knight, who is British, wrote tight thrillers such as 'Pretty Little Things' and David Cronenberg's 'Eastern Promises' before working on Martin Scorsese's Leonardo DiCaprio film 'Shutter Island'.