Gronajny [ɡrɔˈnai̯nɨ] is a village in the administrative district of Gmina Sztum, within Sztum County, Pomeranian Voivodeship, in northern Poland. It lies approximately 7 kilometres (4 mi) north of Sztum and 51 km (32 mi) south-east of the regional capital Gdańsk.

For the history of the region, see History of Pomerania.