Highway 3 starts at a junction with Highway 1 about 100km west of the Highway 2 junction. It goes north to the Mackenzie River, where it crosses via ferry in the summer, and Ice Road in the winter. There is currently a bridge being constructed at this location to replace both the ferry and Ice Road.
From the river crossing, Highway 3 goes generally north to the town of Edzo. It then goes east across the Frank Channel via a bridge. Continuing east, the highway comes to an intersection with a road that leads to Behchoko. The highway continues southeast from here to the capital city, Yellowknife. It terminates at a junction with 48th Ave.