Madisonville is a town in St. Tammany Parish, Louisiana, United States. The population was 677 at the 2000 census. It is part of the New Orleans–Metairie–Kenner Metropolitan Statistical Area.
Madisonville is located at 30°24′26″N 90°9′42″W / 30.40722°N 90.16167°W / 30.40722; -90.16167 (30.407179, -90.161716). Madisonville is on the banks of the Tchefuncte River (see inset), near where the river enters Lake Pontchartrain.
According to the United States Census Bureau, the town has a total area of 2.4 square miles (6.3 km²), all of it land.