| Official Name: | Ilha Grande |
| Subdivision Type: | Country |
| Subdivision Name: | Brazil |
| Subdivision Type1: | Region |
| Subdivision Name1: | Northeast |
| Subdivision Type2: | State |
| Subdivision Name2: | Piauí |
| Leader Title: | Mayor |
| Leader Name: | Joana Darc Sertão (PSDB) |
| Established Title: | Settled |
| Established Date: | January 26, 1997 |
| Area Total Km2: | 134.318 |
| Population As Of: | 2020 [1] |
| Population Total: | 9,457 |
| Population Density Km2: | 64.4 |
| Timezone: | BRT |
| Utc Offset: | -3 |
| Coordinates: | -2.8578°N -41.8208°W |
| Elevation M: | 10 |
Ilha Grande is one of the four coastal cities of Piauí, Brazil. It is also the northernmost city of the state.
The municipality contains part of the Delta do Parnaíba Environmental Protection Area, created in 1996.