Of Icelandic descent, Stefansson lived for a year among the Eskimo in 1906–07, acquiring an intimate knowledge of their language and culture and forming the belief that Europeans could “live off the land” in the Arctic by adopting Eskimo ways. From 1908 to 1912, he and the Canadian zoologist Rudolph M. Anderson carried out ethnographical and zoological studies among the Mackenzie and Copper Eskimo of Coronation Gulf, in Canada's Northwest Territories.

Between 1913 and 1918 Stefansson extended his exploration of the Northwest Territories. His party was divided into two groups; the southern one, under Anderson, did survey and scientific work on the north mainland coast from Alaska eastward to Coronation Gulf, while the northern group travelled extensively in the northwest, discovering the last unknown islands of the Canadian archipelago, Borden, Brock, Meighen, and Longheed. Stefansson's knowledge of the Canadian Arctic led him to predict that the area would become economically important. In World War II he was an adviser to the U.S. government, surveyed defense conditions in Alaska, and prepared reports and manuals for the armed forces. From 1947 he was Arctic consultant at Dartmouth College, Hanover, N.H. He wrote a number of books, including My Life with the Eskimo (1913), The Friendly Arctic (1921), Unsolved Mysteries of the Arctic (1939), and Discovery (1964).