Mestwin [ˈmɛstfin] is a settlement in the administrative district of Gmina Stężyca, within Kartuzy County, Pomeranian Voivodeship, in northern Poland. It lies approximately 4 kilometres (2 mi) east of Stężyca, 19 km (12 mi) south-west of Kartuzy, and 45 km (28 mi) south-west of the regional capital Gdańsk.

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