Kyustendil is a town in the far west of Bulgaria, the capital of the Kyustendil Province, a former bishopric and present Latin Catholic titular see.

Kyustendil Province is a province in southwestern Bulgaria, extending over an area of 3,084.3 km2 (1,190.9 sq mi), and with a population of 163,889. It borders the provinces of Sofia, Pernik, and Blagoevgrad; to the west, its limits coincide with the state borders between Bulgaria and North Macedonia, and between Bulgaria and the Republic of Serbia. The administrative center of the Province is Kyustendil.