South Aceh Regency (Indonesian: Kabupaten Aceh Selatan) is a regency in the Aceh province of Indonesia. It is located on the west coast of the island of Sumatra. The regency covers an area of 4,173.82 square kilometres and had a population of 202,251 at the 2010 Census, 224,588 in 2015 and 232,414 at the 2020 Census; the official estimate as at mid 2023 was 239,475 (comprising 120,187 males and 119,288 females). Its population density was thus 48.5 inhabitants/km at the 2010 census, 53.8 inhabitants/km in 2015, 55.7 inhabitants/km at the 2020 census, and 57.4 inhabitants/km in mid 2023. The seat of the regency government is at Tapaktuan.

While some 60% of the Regency's population are ethically Achinese, some 30% of the people of the regency are Minangkabau-descended Aneuk Jamee and about 10% are ethnically Kluet people.

South Aceh Regency was originally created on 14 November 1956 from the former southeastern districts of West Aceh Regency. On 20 April 1999 its own southeastern districts were in turn split off to create a separate Aceh Singkil Regency, and it was further reduced in size on 10 April 2002 by further districts in the northwest of the regency being split off to create a Southwest Aceh Regency.

At the time of the 2010 Census, the regency was divided administratively into sixteen districts (kecamatan). Later in 2010, two additional districts (Trumon Tengah and Kota Bahagia) were created by being carved out of existing districts. The districts are listed below with their areas and populations at the 2010 Census and the 2020 Census, together with the official estimates for mid 2023. The table also includes the locations of the district administrative centres, the number of villages (gampong) in each district, and its postal codes.

Kode Kemendagri	Name of District (kecamatan)	Area in km	Pop'n Census 2010	Pop'n Census 2020	Pop'n Estimate mid 2023	Admin centre	No. of villages	Post codes
11.01.09	Trumon	765.92	5,614	6,025	6,664	Keude Trumon	12	23774
11.01.16	Trumon Timur (East Trumon)	285.34	10,340	8,528	9,077	Krueng Luas	8	23776
11.01.18	Trumon Tengah (Central Trumon)	123.50		6,692	7,057	Ladang Rimba	10	23775
	Subtotal Trumon area	1,174.76	15,954	21,245	22,798		30
11.01.01	Bakongan	57.62	10,913	5,364	5,482	Bakongan	7	23773
11.01.15	Bakongan Timur (East Bakongan)	73.81	5,208	6,177	6,404	Seubadeh	7	23777
11.01.17	Kota Bahagia (Bahagia Town)	244.63		7,006	7,175	Bukit Gadeng	10	23778
11.01.03	Kluet Selatan (South Kluet)	106.58	12,477	14,380	14,791	Kandang	17	23772
11.01.14	Kluet Timur (East Kluet)	449.03	9,418	10,541	11,044	Paya Dapur	9	23779
11.01.02	Kluet Utara (North Kluet)	73.24	22,271	24,864	25,367	Kota Fajar	21	23771
11.01.10	Pasie Raja	98.11	15,500	18,038	18,598	Ladang Tuha	21	23755
11.01.13	Kluet Tengah (Central Kluet)	801.08	6,120	7,503	7,854	Manggamat	13	23770
11.01.08	Tapaktuan	100.73	22,540	23,190	23,563	Tapaktuan	18	23711 - 23718
11.01.06	Samadua	112.91	14,440	16,055	16,336	Samadua	28	23752
11.01.07	Sawang	189.38	13,679	15,968	16,478	Sawang	15	23753
11.01.05	Meukek	465.06	18,261	20,956	21,519	Meukek	23	23754
11.01.04	Labuanhaji	54.83	11,823	13,389	13,696	Labuhanhaji	16	23761
11.01.11	Labuanhaji Timur (East Labuanhaji)	95.50	9,137	10,032	10,198	Peulumat	12	23758
11.01.12	Labuanhaji Barat (West Labuanhaji)	76.56	15,495	17,706	18,172	Blang Keujeren	15	23757
	Totals for regency	4,173.82	202,251	232,414	239,475	Tapaktuan	260

Note: (a) including small offshore islands including Pulau Trumon.
(b) The 2010 population of Trumon Tengah District is included in the 2010 figure for Trumon Timur District, from which it was split.
(c) The Trumon area which forms the southern 28% of the Regency is adjacent to the city of Subulussalam to the east.
(d) including offshore island of Pulau Kayee.
(e) The 2010 population of Kota Bahagia District is included in the 2010 figure for Bakongan District, from which it was split.
(f) including offshore island of Pulau Batukapal.

• List of regencies and cities of Indonesia

• South Aceh Regency (in Indonesian)

3°08′N 97°27′E / 3.133°N 97.450°E / 3.133; 97.450