Mesplet Lake is a freshwater body in the north-eastern part of Senneterre in Vallée-de-l'Or Regional County Municipality (RCM), in the administrative region of Abitibi-Témiscamingue, in the province of Quebec, in Canada.

The Mesplet Lake hydrographic slope is accessible via a forest road (North-South direction) that passes on the east side of the Saint-Cyr River Valley; in addition, another forest road (East-West direction) serves the north of the Saint-Cyr Lake Biodiversity Reserve.

The surface of Mesplet Lake is usually frozen from early November to mid-May, however, safe ice circulation is generally from mid-November to mid-April.

From there, the current crosses southwards the "Mesplet Pass" (length: 2.1 kilometres (1.3 mi)), which connects it to Cherrier Lake.

The toponym "lac Mesplet" was officialized on December 5, 1968 by the Commission de toponymie du Québec, when it was created.