Białobrzegi County (Polish: powiat białobrzeski) 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 largest town is Białobrzegi, which lies 63 kilometres (39 mi) south of Warsaw.

The only other town in the county is Wyśmierzyce, lying 10 km (6 mi) west of Białobrzegi.

The county covers an area of 639.28 square kilometres (246.8 sq mi).