Ostrowiec County (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 km east of the regional capital Kielce. The county also contains the towns of Ćmielów, lying 10 km south-east of Ostrowiec Świętokrzyski, and Kunów, 9 km west of Ostrowiec Świętokrzyski.
The county covers an area of 616.33 km2. As of 2019 its total population is 109,512, out of which the population of Ostrowiec Świętokrzyski is 68,641, that of Ćmielów is 3,012, that of Kunów is 2,967, and the rural population is 34,892.
Ostrowiec County is bordered by Lipsko County to the north, Opatów County to the south, and Kielce County and Starachowice County to the west.
