He first came to Yellowknife, Northwest Territories in 1938 to work as mill superintendent of Negus Mines Ltd. His family joined him in 1940.
McNiven became the first member of the Legislative Assembly of Northwest Territories from the Arctic; in 1947 he was appointed to the council, for Yellowknife.
The position was effective January 1, 1954 for two years; however, McNiven did not complete his term, resigning in October 1954 to focus on his mine engineering business.
McNiven retired from Eldorado Nuclear Limited in 1965, and died at his Salt Springs, British Columbia home in September 1969.
A tug owned by the Northern Transportation Company Limited, based in the town of Hay River, was also named after him - M/V Jock McNiven.