It came into being on January 1, 1999, as a result of the Polish local government reforms passed in 1998.

Its administrative seat and only town is Tomaszów Mazowiecki, which lies 49 kilometres (30 mi) south-east of the regional capital Łódź.

The county covers an area of 1,025.7 square kilometres (396.0 sq mi).

The county is subdivided into 11 gminas (one urban and 10 rural).

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