Bonthe District is a district that comprises several islands and mainland of the Atlantic Ocean in the Southern Province of Sierra Leone. Bonthe is one of the sixteen districts of Sierra Leone. Its capital is the town of Bonthe Island and its largest city is Bonthe, on Sherbro Island. As of the 2015 census, the district had a population of 200,730. Bonthe District is one of the sixteen districts of Sierra Leone. Bonthe District is subdivided into eleven chiefdoms.
The District occupies a total area of 3,468 km². The District of Bonthe borders the Atlantic Ocean to the west, Moyamba District to the northwest, Bo District to the southeast and Pujehun District to the south. The fifth and current President of Sierra Leone Julius Maada Bio is from Bonthe District.
Bonthe district is largely made up of two main ethnic groups; the Sherbro and Mende. Bonthe district is the native home of the Sherbro people who make up a large minority of the district population. Bonthe district has a large population of both Muslims and Christians.
Bonthe District has one of the world's largest deposits of titanium ore (rutile) in the world. Sierra Rutile Limited, owned by a consortium of US and European investors, began commercial mining operations in Bonthe in early 1979. Due to poor mining policy, the region has little to show for this huge economic potential.