The program "reveals the grit and glory in the wilds of North America, Central America and South America" and will debut in late spring, the network said.
"National Geographic is an iconic brand known for its storytelling, and I am thrilled to be a part of this project," Brolin said in a statement. "This series is absolutely breathtaking, and really inspires my passion for the great outdoors."
"We could not have found a more perfect narrator for this series," said series producer Karen Bass. "Josh really brings to life what our crew captured -- the intimate, the epic and the dramatic stories of wildlife facing the extreme challenges of surviving in the Americas."
Brolin's film credits include "True Grit," "W.," "Milk," "No Country For Old Men" and "The Goonies." He also starred in the TV series "Young Riders."