The first film will star Fast & Furious 6 actor Luke Evans as Bruce Reynolds, the mastermind behind the famous heist.
Reynolds passed away last week at the age of 81, just months before the 50th anniversary of his audacious crime.
Chibnall's new drama will tell the story of how the robbery was inspired, planned, rehearsed and executed, with Reynolds and his team targeting the August Bank Holiday 1963 mail train from Glasgow.
Jack Roth (Bedlam) will play Reynolds's childhood friend Charlie Wilson, with Utopia's Neil Maskell cast as ambitious Ronald 'Buster' Edwards and The Sweeney's Paul Anderson set to play professional Gordon Goody.
Martin Compston (Line of Duty), Del Synnott (The Silence) and Jack Gordon (Panic Button) will also star in the film, directed by Julian Jarrold (The Girl, Appropriate Adult).