Southwest Maluku Regency (Indonesian: Kabupaten Maluku Barat Daya; Indonesian pronunciation: [kabuˌpat̪ɛn maˌluku ˌbarat̪̚ ˈdaja]) is a regency of Maluku Province, Indonesia. Geographically it forms the most eastern portion of the Lesser Sunda Islands, although it has never been administratively included with them, and politically has always comprised a part of the Maluku Province. It comprises a number of islands and island groups in the south of the province, including (running from west to east) Lirang Island, Wetar Island (with almost half of the total land area of the regency), Kisar Island, Romang Island, the Letti Islands, the Damer Islands, the Sermata Islands (formerly called Mdona Hyera) and the Babar Islands. The total land area is 4,581.06 km, and the population was 70,714 at the 2010 Census and 81,928 at the 2020 Census; the official estimate as at mid 2024 was 95,746 (comprising 48,926 males and 46,829 females).
The administrative centre lies at Tiakur on Moa Island (in the Letti Islands), but the largest town is Wonreli (on Kisar Island). These islands were originally part of Maluku Tenggara Regency within Maluku, and then from 4 October 1999 part of Maluku Tenggara Barat Regency when that was created, but from 24 June 2008 became a separate regency within Maluku.
