South Sikkim (Nepali: दक्षिणी सिक्किम) is a district of the Indian state of Sikkim. Its capital is Namchi.

South Sikkim lies at an altitude of 400 to 2000 metres and hence enjoys a temperate climate for most of the year. Major urban centres include Namchi, Ravangla, Jorethang Bazaar and Melli.

It is the most industrialised district in the state, owing to the availability of flat land. Since the geology is stable the roads are in a good condition as compared to other parts of the state which suffer from landslides. The district is also famous for its Sikkim Tea, which is grown near Namchi.

According to the 2011 census South Sikkim district has a population of 146,742, roughly equal to the nation of Saint Lucia. This gives it a ranking of 600th in India (out of a total of 640). The district has a population density of 196 inhabitants per square kilometre (510 /sq mi) . Its population growth rate over the decade 2001-2011 was 11.57 %. South Sikkim has a sex ratio of 914 females for every 1000 males, and a literacy rate of 82.06 %.

Sikkim (/ˈsɪkɨm/; Devanagari: सिक्किम, i.e. the "Goodly Region", or Shikim, Shikimpati or Sikkim;Lepcha: Mayel Lyang; Limbu: Yuksom, "one of the fortified place";Standard Tibetan: འབྲས་ལྗོངས་, Bras Ljongs, Denzong or Demojongs) is a landlocked Indian state located in the Himalayan mountains. The state borders Nepal to the west, China's Tibet Autonomous Region to the north and east, and Bhutan to the southeast, while the state of West Bengal lies to the south.

With around 607,000 inhabitants as of 2011^[update], Sikkim is the least populous state in India and the second-smallest state after Goa in total area, covering approximately 7,096 km² (2,740 sq mi). Sikkim is nonetheless geographically diverse due to its location in the Himalayas; the climate ranges from subtropical to high alpine, and Kangchenjunga, the world's third-highest peak, is located on Sikkim's border with Nepal. Sikkim is a popular tourist destination, owing to its culture, scenery and biodiversity. It also has the only open land border between India and China. Sikkim's capital and largest city is Gangtok.