The Titanic actress will play Maggie Stryder in the upcoming adaptation of Stephenie Meyer's bestselling novel The Host, according to Deadline.
Meyer is also the author of the popular Twilight Saga.
The Host centres on Melanie Stryder, a young girl who becomes possessed by an alien known as Wanderer following an invasion of Earth.
Saoirse Ronan will play the protagonist Melanie. The film also stars Max Irons and Jake Abel, while Diane Kruger joined the cast of the movie in late January.
The Host is scheduled for release on March 29, 2013.