The Ontario Provincial Synod was created in 1912 when the old Province of Canada was divided into two, becoming the present day ecclesiastical provinces of Ontario and Canada. The old Province had come into being in 1861 and included the dioceses of Toronto, Huron, and Ontario, along with Montreal and Quebec. The dioceses of Fredericton and Nova Scotia joined a few years later. The dioceses of Niagara (1875), Ottawa (1996), and Algoma (1873) were added later when they were created. The Diocese of Moosonee was transferred from the Province of Rupert's Land to Ontario in 1935.
The focus of the old Province's work was its Domestic and Foreign Mission Society and its Woman's Auxiliary. With the establishment of the General Synod in 1893 and the transfer to it of this work, much of the reason for the old Province's existence was lost. The dioceses in the civil Province of Ontario wanted to re-focus their efforts on social reform work at the legislature in Toronto but, understandably, the dioceses in Quebec and the Maritimes were not interested in this. This tension led to the division of the old Province in 1912. Bishop James Sweeney summed this up in his Charge to the 1914 Toronto Synod: "The formation of the Provincial Synod of Ontario has made it possible for us to deal wmore effectively as respecting the Church in this Province."