The 43-year-old rapper-actor has closed a deal to join the cast but his role is still undisclosed, according to The Hollywood Reporter.
The film also stars Will Smith, Jai Courtney, Joel Kinnaman and Cara Delevingne.
Jesse Eisenberg and Ben Affleck may make cameo appearances as Lex Luthor and Batman in the film
Based on DC comic, the story centres on imprisoned villains recruited by a government agency to perform black operations in exchange for clemency.
The film is already shooting in Toronto and is scheduled for an August 5, 2016 release in the US.