| Official Name: | South Labuhanbatu Regency |
| Native Name: | لابوهن باتو سلتن Labuhanbatu Selatan |
| Native Name Lang: | id |
| Type: | Regency |
| Motto: | Santun Berkata Bijak Berkarya ("Talk mannerly, work wisely") |
| Coordinates: | 1.9828°N 100.0975°W |
| Subdivision Type: | Country |
| Subdivision Name: | Indonesia |
| Subdivision Type1: | Province |
| Subdivision Name1: | North Sumatra |
| Seat Type: | Regency seat |
| Seat: | Kotapinang |
| Leader Title: | Regent |
| Leader Name: | Wildan Aswan Tanjung |
| Leader Title1: | Vice Regent |
| Leader Name1: | Kholil Jufri Harahap |
| Leader Title2: | Chairman of Council of Representatives |
| Leader Name2: | Eddy Parapat (National Mandate Party) |
| Leader Title3: | Vice Chairmen of Council of Representatives |
| Leader Name3: | Zainal Harahap (PDI-P) and Syahdian Purba (Gerindra) |
| Area Total Km2: | 3596 |
| Population As Of: | mid 2023 estimate |
| Population Total: | 330797 |
| Population Density Km2: | auto |
| Population Footnotes: | [1] |
| Timezone1: | WIB |
| Utc Offset1: | +7 |
South Labuhanbatu Regency (Kabupaten Labuhanbatu Selatan, alternatively Kabupaten Labuhan Batu Selatan) is a regency of North Sumatra Province of Indonesia, created on 21 July 2008 (in accordance with Law No. 22 of 24 June 2008) by being carved out of the southern districts of the existing Labuhanbatu Regency. The new South Labuhanbatu Regency covers an area of 3,596 square kilometres and according to the 2010 census it had a population of 277,673,[2] which rose to 314,094 at the 2020 Census;[3] the official estimate as at mid 2023 was 330,797 (comprising 168,655 males and 162,142 females).[4] Its administrative headquarters are at the town of Kotapinang.
The regency is divided administratively into five districts (kecamatan), tabulated below with their areas and their populations at the 2010 Census[5] and the 2020 Census,[6] together with the official estimates as at mid 2023.[7] The table also includes the location of the district centres, the number of administrative villages in each district (totaling 52 rural desa and 2 urban kelurahan), and its post code.
| Kode Wilayah | Name of District (kecamatan) | Area in km2 | Pop'n Census 2010 | Pop'n Census 2020 | Pop'n Estimate mid 2023 | Admin centre | No. of villages | Post code |
|---|---|---|---|---|---|---|---|---|
| 12.22.04 | Sungai Kanan | 558.96 | 45,407 | 48,447 | 50,148 | Langga Payung | 9 (a) | 21465 |
| 12.22.03 | Torgamba | 1,311.46 | 99,010 | 109,970 | 115,165 | Aek Batu | 14 | 21466 |
| 12.22.01 | Kotapinang | 556.71 | 53,954 | 64,455 | 68,943 | Kotapinang | 10 (b) | 21464 |
| 12.22.05 | Silangkitang | 350.48 | 28,282 | 30,728 | 31,975 | Aek Goti | 6 | 21461 |
| 12.22.02 | Kampung Rakyat | 818.39 | 51,020 | 60,494 | 64,245 | Tanjung Medan | 15 | 21463 |
| Totals | 3,596.00 | 277,673 | 314,094 | 330,797 | Kotapinang | 54 |
Note: (a) including the kelurahan of Langga Payung. (b) including the kelurahan of Kotapinang.