The Nishnawbe-Aski Police Service was formed on January 14, 1994 through a tri-partite agreement between the governments of Canada, Ontario, and the Nishnawbe-Aski Nation.
The Nishnawbe-Aski Police Service gained responsibility for the OPPs Northwest Patrol Unit on June 1, 1998, excluding the communities of Big Trout Lake, Weagamow, Muskrat Dam, and Pikangikum.