Cierżnia [ˈt͡ɕɛrʐɲa] is a settlement in the administrative district of Gmina Wejherowo, within Wejherowo County, Pomeranian Voivodeship, in northern Poland. It lies approximately 11 kilometres (7 mi) south of Wejherowo and 27 km (17 mi) north-west of the regional capital Gdańsk.

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