Tanimbar Islands Regency (Indonesian: Kabupaten Kepulauan Tanimbar) is a regency of Maluku province, Indonesia, consisting primarily of the Tanimbar Islands. The Regency covers a land area of 10,102 km, and it had a population of 105,341 at the 2010 Census and 123,572 at the 2020 Census; the official estimate as at mid 2022 was 124,787. The principal town and administrative centre lies at Saumlaki in Tanimbar Selatan District.

The regency was originally created from the western districts of Southeast Maluku Regency on 4 October 1999 as the "West Southeast Maluku Regency" (Kabupaten Maluku Tenggara Barat). On 24 June 2008 the western districts of this Regency were split off to create the Southwest Maluku Regency (Kabupaten Maluku Barat Daya), leaving only the archipelago of the Tanimbar Islands in the West Southeast Maluku Regency, which was later renamed as Tanimbar Islands Regency (Kabupaten Kepulauan Tanimbar) on 23 January 2019 (2019-01-23); the legislation for this was passed on 28 January 2019.

As at 2010 the regency was divided into nine districts (kecamatan). Subsequently, a tenth district - Molu Maru (consisting of the two northernmost islands in the Tanimbars - Molu and Maru - with a combined land area of 63.8 km) - was by 2017 created from part of the existing Wuorlabobar District. The districts are tabulated below with their areas in km and their populations at the 2010 Census and the 2020 Census, together with the official estimates as at mid 2022. The table also includes the locations of the district administrative centres, the number of administrative villages in each district (totaling 80 rural desa and 2 urban kelurahan), and its postal code. Altogether the archipelago contains 99 islands, of which the principal island is Yamdena.

Kode Wilayah	Name of District (kecamatan)	Area in km	Pop'on Census 2010	Pop'n Census 2020	Pop'n Estimate mid 2022	Admin centre	No. of villages	Post code
81.03.01	Tanimbar Selatan (South Tanimbar)	825.69	31,571	39,085	39,861	Saumlaki	12	97471
81.03.03	Wertambrian	1,298.45	9,708	11,629	11,785	Lorulun	9	97473
81.03.04	Wermaktian	2,941.16	10,905	12,937	13,086	Kamatubun	9	97472
81.03.02	Selaru (Selaru Island)	826.26	12,249	14,263	14,375	Adaut	7	97481
81.03.05	Tanimbar Utara (North Tanimbar)	1,075.74	13,226	13,860	13,687	Ritabel	8	97464
81.03.06	Fordata (Fordata Island)	79.42	4,810	4,770	4,668	Romean	6	97466
81.03.07	Wuar Labobar	654.74	9,907	8,348	8,422	Wunlah	11	97465
81.03.18	Molu Maru			3,692	3,818	Adoda Molo	5	97462
81.03.09	Nirunmas	1,468.30	7,044	7,991	8,013	Tutukembong	50	97463
81.03.08	Kormomolin	933.16	5,921	6,997	7,072	Alusi Kelaan	10	97461
	Totals	10,102.92	105,341	123,572	124,787	Saumlaki	82

Notes: (a) including 2 kelurahan - the towns of Saumlaki and Saumlaki Utara. (b) Yaru District changed its name to Fordata District in 2019.
(c) the area and 2010 population of Molu Maru District are included in the figures for Wuar Labobar District, from which it was split off.