Mierzynko [mjɛˈʐɨnkɔ] is a village in the administrative district of Gmina Gniewino, within Wejherowo County, Pomeranian Voivodeship, in northern Poland. It lies approximately 6 kilometres (4 mi) south-west of Gniewino, 23 km (14 mi) north-west of Wejherowo, and 58 km (36 mi) north-west of the regional capital Gdańsk.

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