Previously it included the municipality of Killarney on the mainland, until this was transferred to Sudbury District in the late 1990s.

Subsequently, more mainland portions were added to Killarney and these, together with Unorganized Mainland Manitoulin District, were also transferred to Sudbury District in 2006, about 1,600 square kilometres (600 sq mi) in all.

Islands included within the district are:[3] Towns: Townships: Unorganized areas: Reserves: As a census division in the 2021 Census of Population conducted by Statistics Canada, the Manitoulin District had a population of 13,935 living in 6,144 of its 9,302 total private dwellings, a change of 5.1% from its 2016 population of 13,255.

All services in the district are provided either by the individual municipalities or directly by the provincial government.

King's Highways: Secondary Highways: The district is served by two weekly community newspapers, the Manitoulin Expositor in Little Current and the Manitoulin West Recorder in Gore Bay; the papers are sister publications both owned and operated by the McCutcheon family.