Mukim Batu Apoi is a mukim in Temburong District, Brunei. It has an area of 222 square kilometres (86 sq mi);^[1] as of 2021, the population was 1,355.^[2]

Sungai Batu Apoi is where Batu Apoi gets its name. Long ago, there was a Murut longhouse there beside the river. Their myth states that a hot rock that was formerly upstream gave Batu Apoi its name. The presence of this rock rendered the entire area inhospitable and unusable to humans. Suddenly a Murut cultural hero appeared one day. He looked at the fiery rock and then tossed it into the sea far away with all of his might. He therefore made the entire region livable and secure so that the Muruts may settle there and live. Firey rock is referred to as Batu Api or Batu Apoi in Murut, a term that has become extensively used up to this point. Apoi is the Murut word for api.^[3] The mukim could be named after Kampong Batu Apoi, one of the villages it encompasses.

The mukim is located in the east of the Temburong District to the centre, bordering Mukim Labu to the north, the Malaysian state of Sarawak to the east, Mukim Amo to the south and Mukim Bangar to the west.^{[citation needed]}

As of 2021 census,^[4] the population was 1,355 with 53% males and 47% females. The mukim had 279 households occupying 241 dwellings. The entire population lived in rural areas.

Previously in 2014, Mukim Batu Apoi has a population of one thousand seven hundred and ninety six people (1,796) which is 950 males and 846 females consisting of Malay, Murut, Iban, Chinese, Dusun and other nationalities. From that number, 186 people received various forms of assistance from the government, namely 125 people received Old Age Pensions, 25 people received assistance from the Community Development Department (JAPEM), 9 people received assistance for the poor, 9 people received assistance for orphans, 5 people received help from new relatives, 10 people received help for handicapped while another 3 people received help for insanity.^[5]

As of 2021, the mukim comprised the following census for the villages:^[2]

Touching on 1 Village 1 Product (1K1P) program, several villages in Mukim Batu Apoi have taken part in the project, which is known for its ambulong (sago) processing. Majlis Perundingan Kampung (MPK) Batu Apoi ambulong has received a favorable response from the public and MPK Batu Apoi often receives visitors especially from outside the district to witness the processing of ambulong. Meanwhile, MPK Tanjong Bungar handles handicraft products.

In 2014, the access road leading to Kampong Peliunan and Kampong Luagan was too small to make it difficult for Fire and Rescue vehicles to enter the villages in case of fire. In addition, DST and B-Mobile mobile phone services in some areas, especially in Kampong Selapon, cannot receive the service at all, as well as some areas in Kampong Batu Apoi. Also found in the mukim are three schools namely Sultan Hashim Batu Apoi Primary School, Selapon Primary School and Negalang Primary School. In addition, Mukim Batu Apoi also has a petrol station in Kampong Negalang and a mosque in Kampong Batu Apoi.^[5]

For the convenience of mukim residents to hold various community activities, the Ministry of Home Affairs through the Temburong District Office has built a community hall in Kampong Batu Apoi and another in Kampong Selapon. Meanwhile, in order to carry out sporting activities, a sports complex, the Temburong Sports Complex, has been built in Mukim Batu Apoi, which is located in Kampong Batu Apoi. The complex, which is used for free, gives many advantages to the residents of the subdistrict and all the residents of the Temburong District.^[5]