The see city of the diocese is Hamilton, with the bishop's cathedra located at Christ's Church Cathedral on James Street North.

Skirting Brantford and the Territory of the Six Nations Confederacy, the line then travels, again, south-westerly to Jarvis and Lake Erie to include the entire Niagara Peninsula.

Major urban centres within its borders are St. Catharines, Niagara Falls, Hamilton, Guelph, Oakville, Milton, Burlington, and Orangeville.

The first Anglican presence in what would become the Diocese of Niagara begin with St Mark's Church in Newark (now Niagara-on-the-Lake), the former capital of Upper Canada.

The courts have generally upheld the diocese as owner of the church buildings and ejected the illegally assumed leadership.