The name of the District is derived from the Subansiri river, a tributary of Mighty Brahmaputra that flows through Raga Circle of that District. Till 1914, the District was a part of North Lakhimpur District of Assam. By the Government of India Notification of 1914, the area cover by this District became a part of Lakhimpur Frontier Tract of the “North East Frontier Tract”. In March, 1919, by another public Notification, the Lakhimpur Frontier Tract along with Western sector was renamed as the “ Balipara Frontier Tract”. In 1946, the district area was curved out of the Balipara Frontier Tract in the name of “Subansiri area” with its Headquarter at North Lakhimpur. In 1954, Subansiri Area was renamed as the “Subansiri Frontier Division” and its Headquarter was later transferred to Ziro. Like other part of NEFA, the District was under the Ministry of External Affairs and overall In-charge was political Officer. On 1st September 1965, the Ministry of Home Affairs took over the Administrative charge of NEFA from the Ministry of External Affairs and Subansiri frontier Division was renamed as Subansiri District and political Officer was redesignated as Deputy Commissioner, Additional Political Officer as Additional Deputy Commissioner, Assistant Political Officer(I) as Assistant Commissioner, Assistant Political Officer(II) as Extra Assistant Commissioner and base Superintendent as circle Officer respectively.
On 13 th May 1980, Subansiri District was bifurcated into Lower and Upper Subansiri District, Upper Subansiri District was formed by covering the area of the then Deporijo Sub- Division and rest of the area of erstwhile Subansiri District was placed under Lower Subansiri. On 22nd September, 1992 Lower Subansiri District was Bifurcated and Papumpare District was formed. By a notification of Govt. Vide No. DAD-30/98 dtd. 16th April 2001, Kurung Kumay District was further Bifurcated and areas covered by the Koloriang Sub- Division and some portion of Ziro (Sadar) Sub-division was formed a separate District. On 1st October 2017, another Kamle district has been formed from administration circles from Lower Subansiri District and three from Upper Subansiri District. The Lower Subansiri circles to be carved out are Raga, Dolungmukh and Kumpurijio.