The total area of the municipality is 344.73 square kilometres (133.10 sq mi), and its population is 51458 as of the 2021 Nepal census.

It is surrounded by Bhojpur District to the north, Dhankuta to the north-east, Sunsari to the east, Saptari to the south and Chaudandigadhi of Udayapur to the west.

Koshi Tappu Wildlife Reserve is a protected area located in Ward No.2 of Belaka Municipality.

It is believed that long years ago this place was ruled by Kirant King & Queen who are collectively called as Mainamaini.

Mainamaini is also famous for the statue of the pig which was built in July 2021 by Belaka municipality for Nrs.sixty Lakh(6000000) Visit Udayapur feel the difference of scenic beauty.