The film will focus on lawman Frank Hamer, who was coaxed into tracking down the well-known outlaws by a consortium of banks in order to stop the pair, reported Deadline.
Hamer was known for surviving around 100 gunfights and is also said to have killed 53 people, but he turned his attentions to the deadly duo after they organised a jailbreak, during which they killed a guard.
John Lee Hancock will direct the project, which looks set to start filming in the first quarter of 2014, while John Fusco has penned the script and Casey Silver will produce. Neeson's forthcoming projects see him lend his voice to children's family film "Khumba" and animated comedy "The Nut Job", in which he will star alongside Brendan Fraser and Katherine Heigl.
Harrelson is to reprise his role as Haymitch Abernathy in "The Hunger Games: Catching Fire" later this year, and will star in thriller "Now You See Me" with Mark Ruffalo and Isla Fisher.