before brazil was officially discovered by european explorers, ilha grande belonged to the tamoio indigenous people who inhabited the country's coastal regions between where cabo frio is today and ubatuba.

according to the diary of italian explorer amerigo vespucci, the second official portuguese expedition to brazil sailed passed ilha grande in early january 1502, as they were heading to what would be their first settlement in the region, arraial do cabo.

ilha grande was later donated to dr. vicente de fonseca, a portuguese nobleman who apparently never took possession of the island not to have the responsibility of governing it, and  permanent european settlement of the island was not reported until 1591.