Historically, the name of the district Lohit is derived from the Sanskrit word Louhitya meaning reddish- or rust-coloured. It is named after the Lohit River which consists of the river valley and hills/mountains to the North and South. Once Lohit was also popularly known as the Mishmi Hills. The region was occupied by the rulers of the Chutiya Kingdom during the medieval period. The place was under the rule of Chutiya rulers for a long period i.e. from early 13th century to the 16th century and during the 19th century it became one of the last territories to be brought under British control after the punitive Abor and Mishmi Expedition in the first decade of 20th century. In June 1980, Dibang Valley district was separated from Lohit. Then on 16th February 2004, Anjaw district was carved out from the northern part of Lohit district bordering Tibet and Myanmar, with its headquarters located at Hawai. Later Anjaw was also carved out under the Arunachal Pradesh Re-organization of Districts Amendment Bill.

Geographically, the district has a total area of 11,402 sq. km. and occupies the Rank 5th in State and 44th in India on the basis of the size. It lies at 27°90'N latitude, 96°17'E longitude and 2185 m altitude. In the year of 2021, there was total 64.64% forest area of the total geographical area. Lohit, Kamlang, Noa Dihing, Tenga pani, Teang, Bereng and Digaru rivers pass through the district. It is surrounded by the Lower Dibang Valley district, China, Tinsukia district of Assam, Anjaw district, Lohit district and Changlang district. 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 1345.5 mm in the year of 2021-22.

Administratively, the district is divided into 8 sub-districts, 2 towns and 300 villages. English is its administrative language. It has administrative headquarters located at Tezu which is situated at the distance of 375 kms from the State Capital.

Demographically, according to the 2011 census, the district has a total number of 29,407 households with a total of 1,45,726 comprising 76,221 are males and 69,505 are females which leads it to rank 3rd in the state and 600th in India. The density of population of the district is 67 (persons per sq km.). The sex ratio is pegged at 912 (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 47,410 including 23,457 are males and 23,953 are females. The percentage of Schedule Tribe is 4.98%. As per 2011 census the percentage of major religions practiced by the people of this region are Hindu with 67.95% and Buddhist with 16.78% of the total population. The population growth rate in the district during the period of 2001-2011 was 16.50% including 13.51% were males and 19.97% were females. According to 2011 census the principal languages in the district are Mishmi and Nepali with 8.43% and 15.01%. In the year 2020 the number of live births in the district was 932 out of which 493 were males and 439 were females. In the same year the number of deaths in the district was 159 out of which 113 were males and 46 were females.

The district is mainly dependent on agricultural sector. Orange, Pineapple and banana are main fruits grown here. Paddy, mazie and wheat are major agricultural products of the district. More than half of its population are engaged in agriculrture in order to earn their livelihood. In the year 2021-22 the gross domestic product in the district was Rs. 3,59,898 lakhs at current price and Rs. 2,12,701 lakhs at constant prices in the year 2011-2012. The net domestic product in the district during the period 2021-22 was Rs. 3,31,961 lakh at current price and Rs. 1,91,606 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. 1,70,365 at current price and Rs. 98,334 at constant prices in the year 2011-2012.

Education wise, according to the 2011 census, the district has a literacy rate of 68.18% including 75.52% are males and 60.04% are females. The total population of literate people is 83,062 comprising 48,380 are males and 34,682 are females. The total number of illiterates in the district is 62,664 comprising 27,841 are males and 34,823 are females. Chow Nanda Memial School, Government Higher Secondary School, Indira Gandhi Government College, Dera Natung Government College, Rajiv Gandhi University and Denning College for Teachers Education are some of the main educational institutions in the district.

Chowna Mein is an Indian politician, belongs to the Indian National Congress Party. He was the member of the Lohit district's Lekang assembly constituency in 1995, 1999 and 2004. Karikho Kri is a member of the Indian National Congress. He is serving as the member of the state Assembly, Tezu.

The district has several beautiful places to visit such as Parasuram Kunda, Buddha-Vihar, Dong, Glow Lake, Hot Spring, District Museum/Craft Centres, Bhismak Nagar, Hawa Camp. Parasuram Kunda is a scared place associated with Parasuram’s matricide. Maker Sankranti, 14 January is a special occasion to visit here by saints. The place is also called 'Prabhu Kuthar'. The district has several Buddha-Vihar , called ‘Chong’ in local language. Typical Thai-architectural style is used to make these vihars and the statues of Lord Buddha. Dong is a small hamlet which has beautiful mountains with snow caps and blue pine forest. Glow Lake is a wonderful place with the surroundings of snow covered mountains and forest. Trekking is also available here. District Museum and Craft Centres is full of a number of books, crafts and handloom products belong to different communities of the state. There is also a Bhismak Nagar which was was founded by king Bhismak. The ruins of the nagar are still available. Hawa Camp is a beautiful picnic place full of mesmerising natural sceneries. It is famous to see the beautiful view of the magnificent Lohit Valley and sunrise and sunset view.