The hamlet was founded and named in honor of Archbishop Gabriel Breynat (often referred to as the "Bishop of the Winds"), a prominent French-born Oblate missionary who administered a vast territory in Canada's North from 1901 to 1943.

Like many areas in Alberta's northern forest and transition zones, settlement picked up as people moved into the region for agriculture, lumbering, and trapping, taking advantage of the expanding northern infrastructure.

Historically, the social and religious anchor of Breynat was its Catholic parish, which shaped much of the community's mid-20th-century development. Before a permanent church existed, visiting priests—such as Father Ernest Lacombe—travelled to the area, holding early masses in local residents' homes starting around 1932. The first St. Thérèse of the Child of Jesus Parish church was constructed in 1934 by resident priests and local volunteers. A rectory followed in 1938. The Post office opened on March 12, 1936. In 1956, a separate school opened in Breynat. Around that same time, a residence was established for the Sisters of Notre Dame de la Croix, a congregation of nuns from Saskatchewan who taught local children. Both the convent and the school operated until they closed in 1967.