The 47-year-old actor is believed to have met with Yoko Ono, the widow of the late Beatle, to discuss playing the role and she was impressed by his plans to learn to sing and master the Liverpool accent, consequently giving the project her "blessing".
A source told the Daily Express newspaper: "Brad already has a writer working on the script. And Yoko has given the project her blessing so long as it`s true to John`s life.
"Brad wants to do all the singing himself and plans to take voice lessons. If he can`t pull it off they`ll use John`s own voice."
Although Brad is reported to want to produce and star in the film, no possible director has been named for the project based on the `Imagine` hitmaker, who was shot in 1980 in New York by crazed fan Mark Chapman.
There are is also no mention of a timescale for the project, although it is unlikely he will be able to film in 2011 due to prior commitments to `Cogan`s Trade` - which shoots in March - and zombie movie `World War Z`.
If made it would not be the first film to be made about John`s life - `Kick-Ass` star Aaron Johnson portrayed the singer in his younger years in 2009`s `Nowhere Boy`.