Sieradz County (Polish: powiat sieradzki) is a unit of territorial administration and local government (powiat) in Łódź Voivodeship, 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 Sieradz, which lies 54 kilometres (34 mi) west of the regional capital Łódź.

The county covers an area of 1,491.04 square kilometres (575.7 sq mi).

The county is subdivided into 11 gminas (one urban, three urban-rural and seven rural).