Bois Blanc Township is a civil township of Mackinac County in the U.S. state of Michigan. As of the 2000 census, Bois Blanc Township's population was 71. The township is coterminous with Bois Blanc Island. The nearby, smaller and uninhabited Round Island is within the civil jurisdiction of the city of Mackinac Island. Bois Blanc Island's ZIP code is 49775.