The district is named after the mighty Subansiri river, a tributary of Mighty Brahmaputra that flows through the Raga Circle of the district. The region was a part of the North Lakhimpur district of Assam until the year 1914. By the Government of India Notification of 1914, the territory cover by the present district became a significant part of Lakhimpur Frontier Tract of the “North East Frontier Tract”. In 1946, the district area was got separated from the Balipara Frontier Tract in the name of “Subansiri area” with its Headquarter located at North Lakhimpur. After sometime in 1954, the name Subansiri area was changed to “Subansiri Frontier Division” and its headquarter was later shifted to Ziro. Then on 13th May, 1980 Subansiri district was divided into two parts such as Lower and Upper Subansiri District. Upper Subansiri district was created by covering the area of the then Deporijo sub-division and rest of the area of erstwhile Subansiri district was placed under the Lower Subansiri. On 22nd September, 1992 Lower Subansiri District was bifurcated and Papumpare District was emerged.

Binny Yanga was a social worker. He is a member of the National Planning Commission of India. He founded an NGO named Oju Welfare Association (OWA) which deals with the issues of child marriage, forced marriage and dowry. She received the Padam Shri award in 2012 by the Government of India.

Geographically, the district has a total area of 9,548 sq. km. area and occupies the rank 7th in State and 77th in India on the basis of the size. It lies at 27°61'N latitude, 93°85'E longitude and 1500 m altitude. In the year 2021, there was a total 87.78% forest area of total geographical area. It is surrounded by the Upper Subansiri district of Arunachal on the North, by Papum Pare District of Arunachal Pradesh and Assam on the South, by West Siang and some part of Upper Subansiri on the East, and by East Kameng district of Arunachal Pradesh on the West. The principal rivers that flow throught the district are Kamala, Subansiri, Khru, Panior, Kime, Panya, Selu, Pugo, Persen, Rein Sipu, Pange and Kile. The climate of the district remains pleasant almost throughout the year. Most of its rainfall occurs in the monsoon season. The actual rainfall in the district was 1048.6 mm in the year of 2021-22.

Administratively, the district is divided into 1 town and 578 villages. English is its administrative language. The district came into existence in the year 1987. It has administrative headquarters located at Ziro which is situated at the distance of 113 kms from the state capital. There are total 6 administrative circles in this district namely Ziro (Sadar), Yachuli, Pistana, Raga, Kamporijo and Dollungmukh. The district comprises 3 blocks such as Ziro-I, Ziro-II and Tamen-Raga. It has 2 legislative assembly constituencies and they are Yachuli and Ziro-Hapoli. Both of these are the part of Arunachal West Lok Sabha constituency.

Demographically, according to 2011 census, the district has a total number of 15,134 households with a total population of 83,030 comprising 41,843 are males and 41,187 are females which leads it to rank 10th in the state and 623 in India. The density of population of the district is 12 (persons per sq km.). The sex ratio is pegged at 984 (females per 1000 males) while the child ratio stands at 966 (females per 1000 males). The schedule tribe population of the district is recorded as 72,911 including 35,803 are males and 37,108 are females. The percentage of Schedule Tribe is 7.66%. As per 2011 census the major religions in the district are Christian and Hindu with 41.43% and 11.50% of the total population. The population growth rate during the period of 2001-2011 was 49.00% including 47.20% were males and 50.86% were females. According to 2011 census the principal languages in the district are Nissi/Dafla and Miri/Mishing with 86.96% and 0.66%. In the year 2020 the number of live births in the district was 1,007 out of which 517 were males and 490 were females. In the same year the number of deaths in the district was 162 out of which 120 were males and 42 were females.

Economically, the district is dependent on agriculture primarily. In the year 2021-22 the gross domestic product in the district was Rs. 2,32,435 lakhs at current price and Rs. 1,38,042 lakhs at constant prices in the year 2011-2012. The net domestic product in the district during the period 2021-22 was Rs. 2,07,228 lakh at current price and Rs. 1,18,741 lakh at constant prices in the year 2011-2012. The Per Capita Income or NDDP, At Factor Cost during the period 2021-22 was Rs. 1,28,204 at current price and Rs. 73,461 at constant prices in the year 2011-2012. Tea, potato, ginger, turmeric, chillies, sugarcane, paddy, wheat, maize, millet, pulses are mainly grown here. Apple, walnut, kiwi, citrus, pineapple, banana are major horticulture products of the region.

Education wise, according to the 2011 census, the district has a literacy rate of 74.35% including 80.53% are males and 68.08% are females. The total population of literate people is 54,057 comprising 29,470 are males and 24,587 are females. The total number of illiterates in the district is 28,973 comprising 12,373 are males and 16,600 are females. District Institute of Education and Training DIET, Indira Gandhi Technological and Medical Science University, Mudo Tmu Memorial B.ED College (MTM College), Saint Claret College and Government College are some of the main educational institutions in the district.

Nikh Kamin is the member of the People's Party of Arunachal. He is also the president of the party. In 2004, he became the member of the Yachuli assembly constituency of the district. Ratan Tama belongs to the Indian National Congress. He was the Member of Rajya Sabha from 1978 to 1984. He also served as the Secretary of Janata Party from the year 1977 to 1978.

The district has several famous historical and religious places to visit. These places are Ziro, Talley Valley, Ranganadi Hydro Project 43 km. Yazali. Every year a number of tourists visit here from the worldwide. Talley Valley Wildlife Sanctuary, Meghna Cave Temple, Kile Pakho, Midey, Ziro Puto, Dolo Mando, Dilopolyang Maniipolyang are tourist spots .that can be seen in Talley Valley.