Siedlce County (Polish: powiat siedlecki) 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.

The county covers an area of 1,603.22 square kilometres (619.0 sq mi).

The county is subdivided into 13 gminas (one urban-rural and 12 rural).

These are listed in the following table, in descending order of population.