The Academy Award-winning actor, who was first linked with the role of Plutarch Heavensbee last month, is now believed to have formally committed to the movie.
"The deal was made right before the Fourth of July holiday," an insider claimed to E! News.
Studio Lionsgate has not commented on the reports and does not usually answer such speculation except in the event of an official announcement - said to be due imminently.
Heavensbee takes over as the new Gamemaker in Catching Fire following the demise of Seneca Crane (Wes Bentley).
Catching Fire is due to start filming this autumn with Francis Lawrence replacing Gary Ross as director.
Jennifer Lawrence, Josh Hutcherson and Liam Hemsworth will reprise their roles from the first movie.
Watch Josh Hutcherson talking to Digital Spy below:
Gallery - 'The Hunger Games' character posters: