About one-sixth of Nagaland is covered by tropical and sub-tropical evergreen forests, consisting of palms, bamboo, rattan, timber, and mahogany. While some forested areas have been cleared for jhum cultivation (shifting agriculture), many scrub forests, rainforests, tall grasslands, and reed-grass marshes still exist. The state is home to several natural reserves, including Ntangki National Park, Pulie Badze Wildlife Sanctuary, Fakim Wildlife Sanctuary, and Rangapahar Reserve Forest.
Nagaland's rich wildlife includes a variety of mammals, such as the slow loris, Assamese macaque, pig-tailed macaque, stump-tailed macaque, rhesus macaque, capped langur, and hoolock gibbon. Carnivorous species found in the region include the Himalayan black bear, sun bear, dhole (wild dog), Bengal tiger (occasionally spotted), Indian leopard, clouded leopard, marbled cat, and golden cat. Large herbivores include the Indian elephant, Indian rhinoceros, gaur (Indian bison), red serow, common and leaf muntjac, eastern hog deer, and sambar deer. The state is also home to unique species such as the Chinese pangolin, Malayan porcupine, Asiatic brush-tailed porcupine, and Hoary bamboo rat, contributing to Nagaland's diverse and vibrant ecosystem.
Nagaland boasts a rich birdlife with over 490 species recorded. The great Indian hornbill holds a special place in Naga culture, while Blyth’s tragopan, a vulnerable species of galliform, is the state bird of Nagaland. This bird is commonly found in Mount Japfü and Dzüko Valley in Kohima District, the Satoi range in Zünheboto District, and Pfütsero in Phek District. The state is also known as the "falcon capital of the world" due to the hundreds of thousands of Amur falcons that stop at Doyang Reservoir to feast on flying termites while migrating from China and Siberia to Africa each year.
The Mithun, a semi-domesticated gaur, is the state animal of Nagaland and has been adopted as the official seal of the Government of Nagaland. It holds significant ritual and cultural value among the Naga tribes. To ensure its conservation and protection, the National Research Centre on Mithun (NRCM) was established by the Indian Council of Agricultural Research (ICAR) in 1988.
Nagaland is also home to 396 species of orchids, belonging to 92 genera, of which 54 species have significant horticultural and medicinal value. This makes the state a biodiversity hotspot with immense potential for ecological conservation and sustainable economic development.