| Bay of Saint-Augustin | |
| Location: | Atsimo-Andrefana, Madagascar |
| Rivers: | Onilahy River |
| Oceans: | Indian Ocean |
| Countries: | Madagascar |
| Pushpin Map: | Madagascar |
| Cities: | Anakao, Saint-Augustin |
The Bay of Saint-Augustin is located on the southwestern coast of Madagascar in the region of Atsimo-Andrefana at the Mozambique Channel. This bay is the mouth of the Onilahy River at a distance of 35 kilometres south of Toliara.