Mattawan is a municipality in the Canadian province of Ontario. Located in the Nipissing District, the municipality had a population of 161 in the Canada 2016 Census.

The municipality has no named communities within its boundaries; all mailing addresses within the municipality are post office boxes assigned to the neighbouring town of Mattawa.

Its main access road is Highway 533, with Highway 656 as a short branch leading to Antoine Mountain and to the Otto Holden Generating Station on the Ottawa River

In 2007, Mattawan, along with the town of Mattawa and the Townships of Papineau-Cameron, Bonfield and the Municipality of Calvin cooperated to create a newly branded Mattawa Voyageur Country tourist region in order to promote the area.