Sibu is a landlocked city located in the central region of Sarawak, Malaysia. It serves as the capital of Sibu District within Sibu Division and is situated on the island of Borneo. Covering an area of 129.5 square kilometres (50.0 sq mi), the city is positioned at the confluence of the Rajang and Igan Rivers, approximately 60 kilometres from the South China Sea and 191.5 kilometres (119 mi) north-east of the state capital, Kuching.

Sarawak is a state of Malaysia. The largest among the 13 states, with an area almost equal to that of Peninsular Malaysia, Sarawak is located in the region of East Malaysia in northwest Borneo, and is bordered by the Malaysian state of Sabah to the northeast, Kalimantan to the south, and Brunei in the north. The state capital, Kuching, is the largest city in Sarawak, the economic centre of the state, and the seat of the Sarawak state government. Other cities and towns in Sarawak include Miri, Sibu, and Bintulu. As of the 2020 Malaysia census, the population of Sarawak was 2.453 million. Sarawak has an equatorial climate with tropical rainforests and abundant animal and plant species. It has several prominent cave systems at Gunung Mulu National Park. Rajang River is the longest river in Malaysia; Bakun Dam, one of the largest dams in Southeast Asia, is located on one of its tributaries, the Balui River. Mount Murud is the highest point in the state. Sarawak is the only state of Malaysia with a Christian majority.