Jolie, 39, will also produce the movie, which is based on a true story, for Skydance Productions, the entertainment website Deadline Hollywood reported.
Eric Roth, who won an Oscar for Forrest Gump, wrote the script.
The story focuses on the Kenyan conservationist Richard Leaky and his battle with ivory poachers in the '80s, the industry paper Variety said.
"I've felt a deep connection to Africa and its culture for much of my life," Jolie said in a statement cited by both Deadline Hollywood and Variety.
Jolie and husband Brad Pitt currently are filming the project By The Sea. Jolie just finished directing the drama Unbroken about the athlete and II World War hero Louis Zamperini, which will hit silver screens in the US in December.
