Grajewo Trzecie [ɡraˈjɛvɔ ˈtʂɛt͡ɕɛ] is a settlement in the administrative district of Gmina Malbork, within Malbork County, Pomeranian Voivodeship, in northern Poland. It lies approximately 5 kilometres (3 mi) north-east of Malbork and 44 km (27 mi) south-east of the regional capital Gdańsk.

Before 1772 the area was part of Kingdom of Poland, in 1772-1919 and 1939-1945 to Prussia and Germany, and in 1920-1939 to Free City of Danzig. For the history of the region, see History of Pomerania.