Longleng district is one of the eleven districts of the Indian state of Nagaland. It is the eighth least populous district in the country (out of 640).

Carved out of Tuensang district, Longleng is tenth district of Nagaland. It is bordered by Mon district in the north, Mokokchung district in the west and Tuensang district in the south. The district’s headquarters is Longleng, which is at an altitude of about 1,066 m above sea level. Tamlu and Longleng are the major towns in the district. Its main river is Dikhu.

According to the 2011 census Longleng district has a population of 50,593,roughly equal to the nation of Saint Kitts and Nevis.This gives it a ranking of 632nd in India (out of a total of 640).Longleng has a sex ratio of 903 females for every 1000 males, and a literacy rate of 73.1%.