Secondary Highway 533, commonly referred to as Highway 533, is a provincially maintained secondary highway in the Canadian province of Ontario. The route begins in the town of Mattawa, at Highway 17, and travels north to Highway 63. Between these two junctions is a large barren expanse of wilderness with almost no habitation. Mattawa is the only community along the route. Highway 533 was assumed in 1956, along with many of the secondary highways in the province. It was later extended to Highway 63 in 1958, establishing the route as it remains today. A roundabout with Highway 17 was opened in late 2011, the first on a provincial highway in Ontario.

Mattawa is a town in northeastern Ontario, Canada at the confluence of the Mattawa and Ottawa Rivers in Nipissing District. The first Europeans to pass through this area were Étienne Brûlé and Samuel de Champlain.