Tunasan is a barangay located in the city of Muntinlupa, Philippines. It serves as the southernmost barangay of Metro Manila and is situated in the southern section of the city, bordering the province of Laguna.
The barangay covers a total land area of 9.596 km2 (3.705 sq mi), making it the largest in the city of Muntinlupa. According to the 2020 census, Tunasan has a population of 61,374 residents.