Grodzisk County (Polish: powiat grodziski) 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 Grodzisk Wielkopolski, which lies 42 kilometres (26 mi) south-west of the regional capital Poznań.

The county also contains the towns of Rakoniewice, lying 13 km (8 mi) south-west of Grodzisk Wielkopolski, and Wielichowo, 13 km (8 mi) south of Grodzisk Wielkopolski.

The county covers an area of 643.72 square kilometres (248.5 sq mi).