Gostyn County (Polish: powiat gostynski) is a unit of territorial administration and local government (powiat) in Greater Poland Voivodeship, west-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 largest town is Gostyń, which lies 59 kilometres (37 mi) south of the regional capital Poznan. The county contains four other towns: Krobia, 11 km (7 mi) south of Gostyn, Poniec, 20 km (12 mi) south-west of Gostyn, Borek Wielkopolski, 17 km (11 mi) east of Gostyn, and Pogorzela, 17 km (11 mi) south-east of Gostyn.
The county covers an area of 810.34 square kilometres (312.9 sq mi). As of 2006 its total population is 75,683, out of which the population of Gostyn is 20,588, that of Krobia is 4,022, that of Poniec is 2,875, that of Borek Wielkopolski is 2,486, that of Pogorzela is 1,974, and the rural population is 43,738.