| São Pedro da Água Branca | |
| Settlement Type: | Municipality |
| Official Name: | The Municipality of São Pedro da Água Branca |
| Subdivision Type: | Country |
| Subdivision Type1: | Region |
| Subdivision Name: |  Brazil |
| Subdivision Name1: | Northeast |
| Subdivision Name2: | Maranhão |
| Leader Title: | Mayor |
| Leader Name: | Idelzio Gonçalves de Oliveira (PTB) |
| Established Title: | Founded |
| Established Date: | June 5, 1996 |
| Area Total Km2: | 720.492 |
| Population As Of: | 2020 [1] |
| Population Total: | 12,735 |
| Population Density Km2: | 15.5 |
| Timezone: | BRT |
| Utc Offset: | -3 |
| Coordinates: | -5.085°N -48.4289°W |
| Blank Name: | HDI (2000) |
| Blank Info: | 0.588 – medium[2] |
São Pedro da Água Branca is the westernmost municipality in the Brazilian state of Maranhão, bordering both Pará and Tocantins states.
The city has one of the most important railway stations on the Carajás Railway line.