Ngawi Regency (Javanese: ꦏꦧꦸꦥꦠꦺꦤ꧀ꦔꦮꦶ) is an inland regency (kabupaten) of Indonesia, on the island of Java. Ngawi is well known around the world for its Pithecanthropus erectus which was found by Eugene Dubois, a Dutchman. Ngawi is located in East Java Province but adjoins Central Java province. Its capital is Ngawi. Ngawi is also the main gate to enter East Java province since there are intersections that connect Surabaya–Bojonegoro–Ngawi–Solo–Jogja–Bandung–Jakarta. The Regency covers an area of 1,394.74 km (538.51 sq mi), and had a population of 817,765 at the 2010 census and 870,057 at the 2020 census; the official estimate as of mid-2023 was 904,094 (comprising 449,052 males and 455,042 females).

Ngawi (town), has the largest central park ("alun-alun") in Indonesia. This large area includes a West Park and an East Park, separated by Merdeka Street. The West Park consists of a football court, a volleyball court, and a ceremonial podium near the main mosque. The East Park consists of a playground area, two tennis courts, a basketball hall, a parking area, a futsal court, a skating place, and a culinary area said to be "the most favorite place visited by Ngawinese". The municipal hall (called Alun-Alun Merdeka) is located in the central part of Ngawi town.

Van Den Bosch Fortress is a central historic site of the Ngawi Regency. It is located at the confluence of the two biggest rivers in East Java: the Solo River and the Madiun River.

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Ngawi has a monsoon tropical climate (Köppen climate classification Am), dry at mid-year, with heavy rain the rest of the year.

Ngawi Regency is divided into nineteen 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 213 rural desa and 4 urban kelurahan - the latter all in Ngawi (town) District), and its postcode.

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 code
35.21.01	Sine	81.43	41,096	44,681	46,793	Sine	15	63264
35.21.02	Ngrambe	67.59	38,750	42,267	44,415	Ngrambe	14	63263
35.21.03	Jogorogo	71.04	38,782	42,307	44,778	Jogorogo	12	63262
35.21.04	Kendal	86.98	44,242	50,055	53,159	Kendal	10	63261
35.21.05	Geneng	54.21	48,975	51,405	52,799	Geneng	13	63271
35.21.18	Gerih	33.81	32,118	36,114	38,155	Gerih	5	63270
35.21.06	Kwadungan	32.63	25,392	26,590	27,206	Kwadungan	14	63283
35.21.14	Pangkur	29.93	26,455	27,489	28,260	Pangkur	9	63282
35.21.07	Karangjati	70.79	46,927	47,427	48,455	Karangjati	17	63284
35.21.15	Bringin	67.72	30,554	30,917	32,122	Bringin	10	63285
35.21.08	Padas	42.29	32,231	34,136	35,122	Padas	12	63280
35.21.19	Kasreman	46.77	23,407	24,469	25,350	Kasreman	8	63281
35.21.09	Ngawi	70.57	79,951	83,445	85,776	Karang Asri	16	63211 - 63218
35.21.10	Paron	106.05	86,014	91,739	95,511	Gelung	14	63253
35.21.11	Kedunggalar	104.40	66,336	71,160	73,520	Kedunggalar	12	63254
35.21.16	Pitu	89.80	27,072	29,469	31,089	Pitu	10	63252
35.21.12	Widodaren	112.38	66,102	70,624	73,403	Walikukun	12	63256
35.21.13	Mantingan	68.70	37,885	38,142	38,023	Mantingan	7	63260
35.21.17	Karanganyar	157.64	25,476	27,621	30,158	Karanganyar	71	63257
	Totals	1,294.74	817,765	870,057	904,094	Ngawi	217

Trinil Museum is about 15 kilometres from Ngawi and near to the Bengawan Solo River. The museum contains a collection of about 1,500 fossils, some of which are a million years old. As of 2013 up to 500 fossils had yet to be identified. In the late 19th century Eugene Dubois found Pithecantropus eretus in the Trinil area.

Researchers found in the Trinil site that the scratch at Pseudodon vondembuschianus trinilensis plain water clam shell aged 500,000 years is the oldest in the world. Although the scratch is perhaps not art, its zig-zag shape is evidence that the scratch is human-made. The clamshell has been found in 1896, but the zig-zag scratch was found in 2014.

• Districts of Ngawi

• Ngawi Regency travel guide from Wikivoyage
• Official website (in Indonesian)