Kyustendil Province (, transliterated Oblast Kyustendil) is a province in southwestern Bulgaria, extending over an area of 3084.3 km² (constituting 2.7% of the total territory of the Republic of Bulgaria), and with a population of 163,889. It borders on the provinces of Sofia, Pernik, and Blagoevgrad; to the west, its limits coincide with the state borders between Bulgaria and the Republic of Macedonia, and between Bulgaria and the Republic of Serbia. The administrative center of the Province is Kyustendil.