Historically, the district was the part of the West zone of Sikkim state before 1963. West zone was divided into West district and South district in the same year. Mr. R.B. Mukhia was the first District Officer of the south Sikkim district.

Baichung Bhutia, an eminent striker in Indian football team of Sikkimese-Bhutia who is popularly known as the torchbearer of the Indian football in the international arena and as Sikkimese Sniper. He is also called as "God's gift to the Indian football" by I. M. Vijayan. Nirmal Chettri is a defending footballer of Kerala Blasters FC in the Indian Super League. Nim Dorjee Tamang is an Indian professional footballer. He plays as a centre back for Shillong Lajong in the I-League. Bijendra Rai is an Indian footballer player in IMG Reliance. Tarundeep Rai is an Indian archer from the Indian Gorkha community. Uttam Rai is a striker in Indian foolball team for the IMG Soccer Academy in Florida, United States and for the India national under-16 football team.

Geographically, the district has a total area of 750 sq. km. area and occupies the rank 4th in State and 606th in India on the basis of the size. It lies at 27°40' N latitude, 88°36' E longitude and 1675 m altitude. In the year 2023, there was a total 75.07% forest area of total geographical area. It is bounded with North Sikkim, West Sikkim, East Sikkim, Darjeeling district and West Bengal. 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 2405.7 mm in the year of 2024-2025.

Administration wise, the district is divided into 2 sub-districts, 2 towns and 148 villages. Nepali is its official language. It has administrative headquarters at Namchi which is situated at a distance of 76 kms from the State Capital.

Demographically, according to the 2011 census, the district has a total number of 30,246 households with a total population of 1,46,850 comprising 76,670 are males and 70,180 are females which causing it to rank 4th in the state and 634th in India. The density of population of the district is 196 (persons per sq km.). The sex ratio is pegged at 915 (females per 1000 males) while the child ratio stands at 953 (females per 1000 males). The population growth rate during the period 2001-2011 was 11.65% out of which 12.35% were males and 10.90% were females. Furthermore, the district has projected population of 1,79,082 comprising 93,623 males and 85,459 females for the year 2026. According to the National Family Health Survey (NFHS-5, 2019–21), the district has an estimated sex ratio of 973 females and a child sex ratio of 1,349 females per 1,000 males. As per 2011 census the principal language in the district is Nepali with 72.66%. According to 2011 census the major religions in the district are Hindu and Buddhist with 57.60% and 23.87% of the total population. In the year 2023 the number of live births in the district was 1,178 out of which 623 were males and 555 were females. In the same year the number of deaths in the district was 747 out of which 468 were males and 279 were females.

The district is mainly dependent on the agricultural sector. Namchi, a significant place in the district produces the tea is globally very famous. Industrially, also the district is quite well developed. In the year 2007-2008 the Gross Domestic Product in the district was Rs. 57,543 lakh at current price and Rs. 40,829 lakh at constant 1999-2000 prices. The Net Domestic Product in the district during the period 2007-2008 was Rs. 47,741 lakh at current price and Rs. 33,976 lakh at constant 1999-2000 prices. The Per Capita Income or NDDP, At Factor Cost in the district during the period 2007-2008 was Rs. 33,106 at current price and Rs. 1,442 at constant 1999-2000 prices.

Education wise, according to 2011 census, the literacy rate in the district is 78.01% out of which 83.3% are males and 70.97% are females. The total literate population of the district is 3,86,351 including 2,35,279 are males and 1,51,072 are females. The total number of illiterates in the district is 40,109 including 17,313 are males and 22,796 are females. In addition, according to the Periodic Labour Force Survey (PLFS) for the period July 2023-June 2024 estimated literacy rate in the district is 93.61% including 95.42% are males and 91.74% are females (Age 7 Years and Above).

Namchi Government College, St. Francis' School, Centre for Computers and Communication Technology, Loyola College of Education, Girls Senior Secondary School, Mount Carmel School, St. Francis' School, Namchi Public School, Tendong Educational Institute and Subuk Primary School are some of the most reputed educational institutions in the district.

Pawan Chamling is the present and fifth chief minister of Sikkim. He is the founder President of the Sikkim Democratic Front. He has honor to be the longest standing Chief Ministers of India and won the legislative assembly elections for five times.

The district has a number of beautiful places which are famous not only within the country but also in the world. Some of the notable places of interest in the district are Namchi, Ravangla, Jorethang, Samdrupste, Solophok, Buddha Park (Sakyamuni Project) and Maenam Wildlife Sanctuary. Every year, a huge number of tourists from the worldwide visit this place in order to enjoy its mesmerizing natural sceneries.