The commune of Chmielnik is a municipal and rural commune located in the county of Kielce in the Świętokrzyskie Province. Its northern part belongs to the mesoregion of the Szydłowskie Foothills (macro-region of the Kielce Highland) and its southern part belongs to the mesoregion of the Połaniecka Basin (macro-region of the Nidziańska Basin). The distance between the southern and northern ends of the commune is around 17 km and between the eastern and western ends is 16 km. The commune of Chmielnik is adjacent to the communes of Morawica and Pierzchnica from the north, the commune of Kije from the west, the commune of Busko-Zdrój from the south and the commune of Gnojno from the east. The commune is crossed by the national road No 73 from Kielce to Tarnów.
Its south-west part is located within the boundaries of the Szaniecki Scenic Park, and the entire eastern part and the north-west one lie within the boundaries of the Chmielnik-Szydłów Protected Landscape Area.