Ostrowiec County (Polish: powiat ostrowiecki) is a unit of territorial administration and local government (powiat) in Świętokrzyskie Voivodeship, south-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 Ostrowiec Świętokrzyski, which lies 56 kilometres (35 mi) east of the regional capital Kielce.

The county also contains the towns of Ćmielów, lying 10 km (6 mi) south-east of Ostrowiec Świętokrzyski, and Kunów, 9 km (6 mi) west of Ostrowiec Świętokrzyski.

The county covers an area of 616.33 square kilometres (238.0 sq mi).