DiCaprio is to play Jay Gatsby, while Maguire will portray Nick Carraway, the entertainment industry trade newspaper said.
Gatsby is the suitor Daisy rejects when she is young because he has no money. Complications ensue when he returns with a fortune years later and attempts to win her back even though she is married. Nick is the mutual friend caught in the middle.
DiCaprio and Luhrmann previously worked together on "William Shakespeare's Romeo + Juliet," and the actor is close friends with Maguire in real life, the publication said.