Khoy, also Romanized as Khoi, is a city in the Central District of Khoy County, West Azerbaijan province, Iran, serving as capital of both the county and the district.

West Azerbaijan province is one of the 31 provinces of Iran, whose capital and largest city is Urmia. It is in the northwest of the country, bordered by Turkey, Iraq and Azerbaijan's Nakhchivan Autonomous Republic, as well as the provinces of East Azerbaijan, Zanjan and Kurdistan. The Iranian province is part of Region 3. It is separated from Armenia by Turkey's short border with the Azerbaijan Republic.