Siedlce County (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. Its administrative seat is the city of Siedlce, although the city is not part of the county (it constitutes a separate city county). The only town in Siedlce County is Mordy, which lies 18 km east of Siedlce.
The county covers an area of 1603.22 km2. As of 2019 its total population is 81,265, out of which the population of Mordy is 1,788 and the rural population is 79,477.
Apart from the city of Siedlce, Siedlce County is also bordered by Węgrów County and Sokołów County to the north, Siemiatycze County to the north-east, Łosice County and Biała Podlaska County to the east, Łuków County to the south, Garwolin County to the south-west, and Mińsk County to the west.
