Lake Manitoba is a large (4,624 km².) lake in central North America, in the Canadian province of Manitoba. It is located about 75 km northwest of the province's capital, Winnipeg.

Communities on the lake include Fairford, Steep Rock, St. Laurent, and Amaranth.

The lake, its shores populated by the Assiniboine Cree, was made known to Europeans by La Vérendrye in the mid-1730s. He and his sons travelled from Fort La Reine through this lake to explore the Saskatchewan river and its environs. Forts were established on both the Saskatchewan and Cedar Lake. It also was part of the route of the fur trade to Hudson Bay.