Lake Nosbonsing (French: Lac Nosbonsing) is a lake in the municipalities of Bonfield, Chisholm, and East Ferris in Nipissing District in Northeastern Ontario, Canada.

[1] It is near the City of North Bay, is the source of the Kaibuskong River, and is in the Saint Lawrence River drainage basin.

The primary inflow, at the south, is Depot Creek.

[5] There are three named communities on the lake: Astorville, at the western tip, and Nosbonsing at the north, both in East Ferris; and Bonfield, at the northeast at the outflow of the Kaibuskong River, in Bonfield.

The original Canadian Pacific Railway transcontinental main line runs along the northeast shore from the communities of Bonfield to Nosbonsing.