Sepaku (Indonesian pronunciation: [səˈpaku]) is a district of Penajam North Paser Regency, East Kalimantan, Indonesia. As of 2023, it was inhabited by 40,322 people, an increase from 39,738 people in 2022, and currently has the total area of 1,172.36 km. It was split from Penajam on 11 June 1996. Its district seat is located at the village of Tengin Baru.

Sepaku is notable for being the site of the future national capital of Nusantara, although only 10% to 20% of the current total area is being included. The district also borders Balikpapan (specifically the district of West Balikpapan) to east, Kutai Kartanegara Regency to the north, West Kutai Regency to the northwest, and Paser Regency to the southwest.

According to the website of the Suka Raja village, Sepaku (and also the eponymous urban village of Sepaku) is named after the abundance of ferns (paku) in that district.

Before its establishment in its current form, Sepaku was known for being a destination for transmigrants, mostly of Javanese ethnicity, with the land established in 1968 by a gubernatorial decree. Its settlement started on 26 August 1975 at the village of Sepaku I (now Bukit Raya), and ended in 1984 at Semoi III (now Sukomulyo). Along with Penajam (then known as Balikpapan Seberang), it was part of Balikpapan until 1987. Another transmigration programs occurred in 1991 and 1998.

On 11 June 1996, following the enactment of the government regulation number 38, Sepaku was formed from the northern parts of Penajam, along with the formation of 12 others in East and North Kalimantan. Its formation was inaugurated on 25 September 1996 by then East Kalimantan governor H. Muhammad Ardans [id]. On 5 March 1999, seven numbered villages were renamed by a gubernatorial decree, and only one (Semoi II or Semoi Dua) currently retains its name:

• Sepaku I became Bukit Raya
• Sepaku II became Suka Raja
• Sepaku III became Tengin Baru
• Sepaku IV became Bumi Harapan
• Semoi I became Argo Mulyo
• Semoi III became Suko Mulyo
• Semoi IV became Wonosari

Since 2002, Sepaku has been a part of Penajam North Paser (PPU), after it split from Paser Regency (then Pasir). Eight years later, on 14 April 2010, Binuang and Telemow villages were formed from parts of Maridan by local regulation number 6. Before being chosen for the site of the future Indonesian capital in 2019, there had been demands from the district to secede from PPU due to lags in development.

Sepaku is divided into the following 15 villages (the rest are rural desa, and 4 of them are urban kelurahan, marked with asterisks):

No.	Regional code (Kode wilayah)	Name	Area (km)	Population (2023)	Population (2022)	RW
1	64.09.04.1007	Maridan*	37.05	4,165	4,189
2	64.09.04.1008	Mentawir*	132.24	777	740
3	64.09.04.1006	Pemaluan*	367.18	1,904	1,834
4	64.09.04.2004	Bumi Harapan	15.00	2,380	2,322	2
5	64.09.04.2012	Wonosari	33.41	1,317	1,312	2
6	64.09.04.2010	Semoi Dua	74.47	3,407	3,386	4
7	64.09.04.2009	Argo Mulyo	36.14	3,387	3,349	5
8	64.09.04.2011	Suko Mulyo	27.11	2,214	2,166	3
9	64.09.04.2001	Tengin Baru	43.48	4,306	4,245	5
10	64.09.04.2003	Sukaraja	77.38	4,263	4,123	5
11	64.09.04.2002	Bukit Raya	185.34	3,119	3,049	2
12	64.09.04.1005	Sepaku*	133.97	2,021	1,986
13	64.09.04.2013	Karang Jinawi	13.85	1,163	1,128	2
14	64.09.04.2014	Telemow	4.82	3,655	3,719	3
15	64.09.04.2015	Binuang	17.65	2,244	2,190	2
Totals	64.09.04	Sepaku	1,172.36	40,322	39,738	35

The following are the list of district heads (camat) of Sepaku:

#	Name	Took office	Left office
1	Baharuddin	1997	2000
2	Tasmad Hariady	2000	2002
3	Hardani Har	2002	2004
4	Suhardi	2004	2005
5	Muhammad	2005	2009
6	Nurzaman	2009	2011
7	Daman	2011	2013
8	Risman Abdul	2013	Incumbent

As of 2022/2023 school year, Sepaku had 15 private kindergartens, 29 elementary schools (4 of them were private), 8 junior high schools (3 were private), a madrasah tsanawiyah (an Islamic counterpart of the former), 2 senior high schools (each private and public), and a private madrasah aliyah (an Islamic counterpart of the former).

As of 2022, Sepaku had 4 public health centers (puskesmas), 2 pharmacies, and each one hospital and polyclinic. The first hospital at the district, Pratama Regional Hospital, was inaugurated on 5 August 2021 by the regional secretary of PPU, Muliadi, and it began to provide health services on 10 January 2022.