| Piratini | |
| Settlement Type: | Municipality |
| Pushpin Map: | Brazil |
| Pushpin Mapsize: | 250 |
| Pushpin Map Caption: | Location in Brazil |
| Subdivision Type: | Country |
| Subdivision Type1: | State |
| Subdivision Type2: | Mesoregion |
| Subdivision Type3: | Microregion |
| Subdivision Name: |  Brazil |
| Subdivision Name1: | Rio Grande do Sul |
| Subdivision Name2: | Sudoeste Rio-grandense |
| Subdivision Name3: | Serras de Sudeste |
| Leader Title: | Mayor |
| Leader Name: | Vilso Agnelo da Silva Gomes |
| Established Title: | Founded |
| Established Date: | 6 July 1789 |
| Area Total Km2: | 3561.48 |
| Population As Of: | 2020 [1] |
| Population Total: | 20,704 |
| Population Demonym: | Piratinenses |
| Population Density Km2: | auto |
| Timezone: | BRT |
| Utc Offset: | -3 |
| Coordinates: | -31.4478°N -53.1039°W |
| Elevation M: | 349 |
Piratini is a city in the Brazilian state of Rio Grande do Sul with a population of some 21,000. It is the former capital of the short-lived Riograndense Republic which was proclaimed on September 11, 1836.