Highway 520 begins in Ardbeg as a continuation of the local Clear Lake Road, and travels south then east about 500 metres (1,600 ft) to reach a level crossing of the Canadian National Railway (CN) line at Ardbeg flag stop.^[2] It continues east, then south through a sparsely populated region of the Canadian Shield, though providing access to several First Nation villages. Upon reaching Highway 124 at Dunchurch, the two routes travel east, concurrently, for 15.4 kilometres (9.6 mi).^[1] Highway 520 then branches to the south, meets Highway 510 and passes through the village of Magnetawan.^[3]

Southeast of Magnetawan, the highway winds along the northern shore of Cecebe Lake, bisecting several small communities en route. It enters the town of Burk's Falls, where it is known as Ryerson Centre Road. Passing beneath the Burk's Falls Bypass of Highway 11, Highway 520 parallels the Magnetawan River briefly then turns south onto Ontario Street, the former alignment of Highway 11. It crosses the river and travels through the centre of the town, meeting the bypass south of it. Highway 520 ends at an interchange with Highway 11, at Exit 257, south of Burk's Falls.^[3] The portion of Highway 520 from the intersection of Ontario Street south to the Burk's Falls town limits is maintained under a Connecting Link agreement.

Highway 520 is one of many Secondary Highways assigned a route number in 1956.^[4] Prior to this time, the route was a numbered, but unposted Development Road maintained by the Department of Highways.

The following table lists the major junctions along Highway 520, as noted by the Ministry of Transportation of Ontario.^[1] The entire route is located in Parry Sound District.^[3]