In 1817, settlers at the Red River Colony petitioned Joseph-Octave Plessis, Bishop of Quebec, for a resident priest.

Dumoulin and seminarian Guilaume Etienne Edge to open a mission on the Red River in present-day Manitoba, where the majority of settlers were Irish and Scottish Catholics.

[5] The area separated from Archdiocese of Québec comprised the entire territory west of the Great Lakes and as far north as the Pole.

[7] On April 8, 1862 the Apostolic Vicariate of Athabaska Mackenzie was erected from territory split off from the Diocese of Saint-Boniface.

On September 22, 1871 Saint-Boniface was raised to a metropolitan archdiocese, while at the same time, it lost territory with the establishment of the Diocese of Saint Albert.

The area of the Archdiocese was again reduced on July 11, 1882 as part of its contribution to the Apostolic Vicariate of Pontiac, but was increased in 1889 with the reassignment of some land from the Diocese of Saint Albert.

In 1900, under Archbishop Adélard Langevin, Holy Ghost Parish was established in North Winnipeg to serve Polish Catholics.

[8] The archdiocese covers much of the province south of Lake Winnipeg and east of the Red River.

Saint Boniface is a city ward of Winnipeg that sits on the east side of the Red River, and the area is a traditional home of Franco-Manitobans.