The young actor will portray Coe, now a Lord, in a film about the running man's track rivalry with fellow British athlete Steve Ovett.
Radcliffe will reteam with his Woman in Black director James Watkins for the project, titled Gold.
Producers are still casting the actor who will portray Ovett in the film, which is being adapted from Pat Butcher's book The Perfect Distance by Slumdog Millionaire Oscar winner Simon Beaufoy.
The filmmaker recently told the Bbc he's thoroughly enjoying researching Coe and Ovett's rivalry: "I hadn't realised how good it was until you dig into their past. They were fantastically different athletes and different people. And they rarely met... apart from on the track."
Filming is scheduled to begin in the U.K. and Russia next spring (Apr13).