Trenggalek Regency (Indonesian: Kabupaten Trenggalek; Javanese: ꦏꦧꦸꦥꦠꦺꦤ꧀ꦠꦿꦼꦁꦒꦭꦺꦏ꧀) is a regency (kabupaten) in East Java, Indonesia.

This regency has an area of 1,261.40 km and had a population of 674,411 residents at the 2010 Census and 731,125 at the 2020 Census; the official estimate as of mid-2023 was 756,109. It is located on the southern shore of East Java and is surrounded by three regencies: Ponorogo Regency to the northwest; Pacitan Regency to the southwest; and Tulungagung Regency to the east. The administrative centre is located in the district (kecamatan) of Trenggalek.

Trenggalek is a regency that is located on the southern shore of Java island and has the following geographical boundaries:

• To the northwest: Ponorogo Regency;
• To the southwest: Pacitan Regency;
• To the east: Tulungagung Regency;
• To the south: Indian Ocean, and
• To the north: Mount Wilis.

The Regency is divided into fourteen districts (kecamatan), tabulated below with their areas and their population totals from the 2010 Census and the 2020 Census, together with the official estimates as of mid-2023. The table also includes the locations of the district headquarters, the number of administrative villages in each district (totaling 152 rural desa and 5 urban kelurahan - the latter all in Trenggalek (town) District), and its postal codes.

Kode Wilayah	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
35.03.01	Panggul	131.56	69,325	78,344	81,492	Wonocoyo	17	66364
35.03.02	Munjungan	154.80	46,916	52,908	54,498	Munjungan	11	66365
35.03.08	Watulimo	154.44	62,625	70,002	72,855	Prigi	12	66382
35.03.07	Kampak	79.00	35,743	37,201	38,453	Bendoagung	7	66373
35.03.04	Dongko	141.20	59,248	65,505	68,272	Dongko	10	66363
35.03.03	Pule	118.12	50,908	55,822	57,843	Pule	10	66362
35.03.06	Karangan	50.92	45,432	49,930	50,853	Karangan	12	66361
35.03.14	Suruh	50.72	24,546	26,028	26,795	Suruh	7	66360
35.03.10	Gandusari	54.96	49,082	52,560	54,167	Gandusari	11	66372
35.03.13	Durenan	57.16	48,985	51,320	51,917	Kendalrejo	14	66381
35.03.12	Pogalan	41.80	47,951	52,234	53,737	Ngadirenggo	10	66371
35.03.11	Trenggalek (town)	61.16	62,606	64,306	66,887	Ngantru	15	66311 - 66319
35.03.05	Tugu	74.72	45,764	47,829	49,749	Gondang	15	66352
35.03.09	Bendungan	90.84	25,280	27,136	28,591	Dompyong	8	66351
	Totals	1,261,40	674,411	731,125	756,109		157

Notes: (a) including 11 small offshore islands. (b) including 23 small offshore islands. (c) including 23 small offshore islands.
(d) comprising 5 urban kelurahan (Kelutan, Ngantru, Sumbergedong, Surodakan and Tamanan) and 10 desa.
(e) except for the village of Banaran, which has a post code of 66318.

Agricultural produce in the area includes rice, corn, cassava, soya beans,and legumes. Plantations produce sugar cane, cloves, durians, salak, mangosteens, and rambutans. Industrial outputs include soy sauce, syrup, tapioca, anchovies, batik, snacks, cigarettes, sawmill, building materials, roofs, and tofu.

Trenggalek has several tourist sites, including beaches (Pantai), caves, and mountain ranges.

1. Gua Lowo is a cave with examples of stalactites and stalagmites. Based on a cave expert, Mr. Gilbert Manthovani and Dr. Robert K. Kho in 1984, it was declared that Guo Lowo is the biggest natural cave in Southeast Asia with approximately 800  meters of length, nine main rooms, and some small rooms. Guo Lowo means "bat cave", owing to the many bats living here when it was first discovered.
2. Pantai Prigi. This beach is known for its rock formations. There is also a fish market and a harbor.
3. Pantai Pasir Putih. Means "white sand beach" and is located adjacent to the Prigi beach.
4. Pantai Pelang. This beach has a waterfall and some tiny islands.
5. Larung Sembonyo. This traditional ceremony is held annually.
6. Pemandian Tapan. This bathing place is located in Karangan and the natural water source comes directly from the mountain ranges.
7. Upacara Dam Bagong. The bull's head is swept away in Kali Bagong (Bagong river) in this annually-held ceremony.
8. Candi Brongkah. It is a temple that tells the history of Trenggalek.
9. Alun-alun Kota. It is the central park in the middle of the city. It also has a playground and snack vendors nearby.
10. Tri Turonggo Yakso. It is a typical traditional dance of Trenggalek. The dance belongs to the traditional dance called "jaranan" which also founded another region. Turonggo Yakso symbolizes the victory of villages in driving away from the devil.

• 
  A view over Pucanganak village in western Trenggalek
• 
  Traditional boats are popular among tourists on Prigi beach
• 
  Sunset on Prigi pier
• 
  Skyline of Trenggalek Kota
• 
  Highlands in western Trenggalek
• 
  Plantations in a typical village
• 
  Winding road to Bendungan district in northern Trenggalek
• 
  Village in Trenggalek

• List of regencies and cities of Indonesia