Lake Pyaozero (, ) is a large freshwater lake in the Republic of Karelia, northwestern part of Russia. It is located at and has an area of 659 km². There are many islands on the lake with total area of 186 km². Among the rivers that flow into lake Pyaozero is the river Oulankajoki that begins in Finland, where one of its tributaries is the river Kitkanjoki that begins from lake Kitkajärvi in Finland. From south also the waters of Lake Topozero in the Republic of Karelia flow into the Lake Pyaozero.