Mielno is a coastal town in Koszalin County, West Pomeranian Voivodeship, in north-western Poland. It is the seat of the gmina (administrative district) called Gmina Mielno. It lies approximately 12 kilometres (7 mi) north-west of Koszalin and 135 km (84 mi) north-east of the regional capital Szczecin. The town has a population of 3,200.

Mielno is a well-known tourist destination with sandy beaches on the Baltic Sea coast. It lies on a spit between the sea and the large Jamno lake. It is contiguous with the neighbouring resort of Uniescie.

Gaski is one of three sites selected by Polish power company PGE in November 2011 to host a nuclear power station with a capacity of 3 gigawatts. In February 2012, residents voted overwhelmingly against the plan. Some 94 percent of the 2,389 people who took part in a referendum opposed the plant and only 5 percent supported it.