McHenry Township is bordered by Brown Township to the north, Pine Township to the east, Cummings Township to the south and Clinton County to the west [REF].
According to the United States Census Bureau, the township has a total area of 76.5 square miles (198.1 km2).76.0 square miles (196.9 km2) of it is land and 0.5 square miles (1.2 km2) of it (0.61%) is water.