Gostynin County is a unit of territorial administration and local government (powiat) in Masovian Voivodeship, east-central Poland. It came into being on January 1, 1999, as a result of the Polish local government reforms passed in 1998. Its administrative seat and only town is Gostynin, which lies 107 km west of Warsaw. The county covers an area of 615.56 km2. As of 2019, its total population was 43,099, out of which the population of Gostynin was 18,588, and the rural population was 24,511.

Neighbouring counties

Gostynin County is bordered by Płock County to the north-east, Sochaczew County to the east, Łowicz County to the south-east, Kutno County to the south and Włocławek County to the north-west.

Administrative division

The county is subdivided into five gminas (one urban and four rural). These are listed in the following table, in descending order of population.