In 1823, McLeod was assigned as manager of the Fort Simpson fur trading post, located at the junction of the Liard and Mackenzie Rivers, where he would remain nine years as deputy to the Chief Trader.
In 1823-24, McLeod completed explorations of nine mountain ranges adjacent to the South Nahanni River, during which he opened trading relations with the Kaska First Nation.
Following this trip, Governor George Simpson briefly transferred McLeod to the Montreal Department, and then back to the Mackenzie River District.
Journeying over the Arctic-Pacific divide, McLeod also partially descended the Stikine River, encountering coastal First Nations tribes, engaged in trading with the Russians.
After twenty-six years as a fur trader in far-flung remote regions of the continent, the forty-seven-year-old McLeod retired from the Hudson's Bay Company in 1842 and returned to Great Britain.