| Official Name: | Southwest Sumba Regency |
| Native Name: | Kabupaten Sumba Barat Daya |
| Settlement Type: | Regency |
| Pushpin Map: | Indonesia_Sumba#Indonesia_Lesser Sunda_Islands#Indonesia |
| Pushpin Label Position: | top |
| Pushpin Map Caption: | Location in Sumba, Lesser Sunda Islands and Indonesia |
| Subdivision Type: | Country |
| Subdivision Name: |  Indonesia |
| Subdivision Type1: | Region |
| Subdivision Name1: | Lesser Sunda Islands |
| Subdivision Type2: | Province |
| Seat Type: | Capital |
| Seat: | Tambolaka |
| Leader Title: | Regent |
| Leader Name: | Markus Dairo Tallu |
| Leader Title1: | Vice Regent |
| Leader Name1: | Ndara Tanggu Kaha |
| Unit Pref: | Imperial |
| Area Total Km2: | 1445.32 |
| Population As Of: | mid 2023 estimate |
| Population Footnotes: | [1] |
| Population Total: | 322073 |
| Population Density Km2: | auto |
| Coordinates: | -9.5622°N 119.0891°W |
| Area Code Type: | Area code |
| Area Code: | (+62) 387 |
Southwest Sumba Regency (Indonesian: Kabupaten Sumba Barat Daya) is a regency on Sumba Island in East Nusa Tenggara province of Indonesia. Established on 2 January 2007 out of parts of West Sumba Regency, the regency has its seat (capital) in Tambolaka. Its population was 283,818 in the 2010 decennial census[2] and had risen to 303,650 at the 2020 census;[3] the official estimate as at mid 2022 was 322,073 (comprising 164,825 males and 157,248 females[4]
The Southwest Sumba Regency when created was composed of eight districts (kecamatan), but since 2010, three additional districts have been created within the Regency, by the splitting of existing districts. The areas (in km2) and the populations of the districts at the 2010 census[5] and the 2020 census[6] are listed below, together with the official estimates as at mid 2023.[7] The table also includes the locations of the district administrative centres, and the number of administrative villages in each district (totaling 173 rural desa and 2 urban kelurahan - the latter both in Kota Tambolaka District).
| 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 | |
|---|---|---|---|---|---|---|---|---|---|
| 53.18.06 | Kodi Bangedo | 73.22 | 36,057 | 17,220 | 17,836 | Walla Ndimu | 15 | 87264 | |
| 53.18.11 | Kodi Balaghar | 144.67 | (a) | 17,980 | 18,624 | Panenggo Ede | 14 | 87262 | |
| 53.18.07 | Kodi | 111.86 | 31,223 | 30,010 | 31,090 | Bondo Kodi | 19 | 87261 | |
| 53.18.08 | Kodi Utara (North Kodi) | 243.82 | 50,864 | 48,860 | 51,176 | Kori | 21 | 87260 | |
| Totals western (Kodi) part | 573.57 | 118,149 | 114,070 | 118,726 | 69 | ||||
| 53.18.05 | Wewewa Selatan (South Wewewa) | 174.14 | 21,691 | 22,800 | 23,962 | Tena Teke | 14 | 87263 | |
| 53.18.04 | Wewewa Barat (West Wewewa) | 147.34 | 45,482 | 42,270 | 46,017 | Waimangura | 20 | 87253 | |
| 53.18.03 | Wewewa Timur (East Wewewa) | 139.88 | 53,911 | 26,410 | 27,626 | Elopada | 19 | 87250 | |
| 53.18.10 | Wewewa Tengah (Central Wewewa) | 109.67 | (b) | 31,160 | 33,170 | Ndapa Taka | 20 | 87252 | |
| 53.18.02 | Wewewa Utara (North Wewewa) | 63.26 | 11,638 | 12,640 | 13,406 | Palla | 12 | 87251 | |
| 53.18.01 | Loura | 138.51 | 34,037 | 18,540 | 22,092 | Karuni | 11 | 87254 | |
| 53.18.09 | Kota Tambolaka (Tambolaka town) | 98.95 | (b) | 35,790 | 37,074 | Tambolaka | 10 | 87255 | |
| Totals eastern (Wewewa) part | 871.75 | 166,759 | 191,762 | 203,347 | 106 |
Notes: (a) The 2010 census populations of Kodi Balaghar is included with the figures for Kodi Bangedo, from which it was split.
(b) The 2010 census populations of Kota Tambolaka and Wewewa Tengah Districts are included with the figures for the districts from which they were split.
(c) including the two kelurahan of Langga Lero and Waitabula.
thumb|Wainyapu
Several tourist attractions in this district have been widely explored and visited by a variety of local and foreign tourists, but there are only a few who have access to roads and adequate facilities and infrastructure available, namely Mananga Aba Beach, Mbawana beach, Oro Beach, Kawona Beach, Newa Beach, Pantai Waikelo, Sumba Cultural Home, Lake Saltwater Weekuri, and Pabeti Waterfall.
This district includes several traditional villages such as Wainyapu and on the south-west coast, and others inland. Wainyapu is particularly rich in dolmens, which - as of 2021 - are still built for collective graves.