Aceh Singkil Regency is a regency in the Aceh province of Indonesia. It is situated largely on the island of Sumatra, but also includes the offshore Banyak Islands, the largest of which is Tuangku, with the principal town of Alaban. The regency was created on 20 April 1999 from the former southern districts of South Aceh Regency. Until 2007 it included the large town of Subulussalam, but on 2 January of that year that town was split off to become an autonomous city. The seat of the Aceh Singkil Regency government is at the port of Singkil on the Sumatra coast. The Regency now covers an area of 1,857.88 km2, and had a population of 102,509 at the 2010 Census, rising to 114,326 at the 2015 Census and to 126,514 at the 2020 Census; the official estimate as at mid 2023 was 135,435.