Binnenmaas was a municipality in the western Netherlands, in the province of South Holland. The municipality had a population of in 2019, and covers an area of 75.57 km² of which 6.31 km² is water. It is named after the lake of the same name.
The municipality was formed on January 1, 1984, by the merger of the municipalities Puttershoek, Maasdam, Mijnsheerenland, Westmaas, and Heinenoord. On January 1, 2007, the municipality 's-Gravendeel was added to Binnenmaas. On January 1, 2019 it was merged with Cromstrijen, Korendijk, Oud-Beijerland, and Strijen to form the municipality of Hoeksche Waard.
The municipality of Binnenmaas consists of the following communities: Blaaksedijk, De Wacht, Goidschalxoord, 's-Gravendeel, Greup, Heinenoord, Kuipersveer, Maasdam, Maasdijk, Mijnsheerenland, Puttershoek, Reedijk, Schenkeldijk, Sint Anthoniepolder, Westdijk, Westmaas and Zwanegat.