Hardy conceived the untitled animal-trafficking drama, which will be made through Warner Bros, according to The Hollywood Reporter.
The film is intended to have a similar format to Steven Soderbergh's Traffic with multiple storylines exploring the different aspects of the illegal trade, from the war against poachers in Africa to contraband materials arriving in Paris fashion houses.
The project is yet to secure a writer. It is unclear whether Hardy, DiCaprio or Maguire will act in the film.
Hardy and DiCaprio both featured in Christopher Nolan's Inception. The latter will also star shortly in The Great Gatsby alongside Maguire.
The film was inspired by Lawless star Hardy's friendship wtih former Special Forces operatives who have become anti-poaching fighters.
DiCaprio is also a long-time animal rights activist.
Watch Leonardo DiCaprio in a trailer for The Great Gatsby below: