The young missionary Petitot traveled with Bishop Alexandre-Antonin Taché from Marseilles via Liverpool (where they were joined by another two Oblates, Constantine Scollen and John Duffy) and Montreal to St Boniface (Winnipeg) arriving there on 26 May 1862.

By August 1862, he had traveled to Great Slave Lake in Canada's Northwest Territories with the Hudson's Bay Brigade Trail.

The following year, in 1875, he spoke at the inaugural International Congress of Americanists in Nancy, France making a strong case for the Asiatic origin of Inuit and North American Indians.

He was awarded a silver medal by the Société de Géographie for his Arctic maps, including the partially traveled Hornaday River, though he referred to it as Rivière La Roncière-le Noury,[9] named in honor of the president of the Société de Géographie.

After two years in France, Petitot returned to the North, mostly helping and studying the people of the Great Slave Lake area.

In late 1881, at Fort Pitt (Sask) he "married" Margarite (Margarita) Valette, a mature Metis woman.