Long Bagun (Indonesian pronunciation: [ˈlɔŋ ˈbaɡʊn]) is a district of the Mahakam Ulu Regency, East Kalimantan, Indonesia.

As of 2023, it was inhabited by 15,231 people, and currently has the total area of 4,801.22 km2.

Its district seat is located at Ujoh Bilang, which is also known as the regency's capital.

[3] Long Bagun is divided into the following 11 villages (kampung):[3] As of 2023, Long Bagun was populated by 15,231 people: 7,172 males and 8,059 females.

[3] Religion in Long Bagun (2022)[4] As of 2022, by far the largest religious group in Long Bagun were Catholics (8,899 people), followed by significant minorities including Muslims (4,483), Protestants (2,311 people), Hindus (8 people) and Buddhists (2 people).