Montes Azules Biosphere Reserve is a protected natural area in Chiapas state of southern Mexico.

The reserve protects 3312 km2 of the Lacandon Jungle, a lowland tropical rainforest.

Montes Azules Biosphere reserve adjoins Lacan-Tun Biosphere Reserve on the east, and is bounded by the Lacantun River, a tributary of the Usumacinta, on the south.

Native reptiles include Morelet's crocodile (Crocodylus moreletii).

The reserve is currently threatened by timber cutting and people setting fire to the forest to clear areas for cattle raising and farming.