Khonj County () is in Fars province, Iran. Its capital is the city of Khonj.
Khonj was traditionally part of the region of Irahistan. Khonj's inhabitants are Achomi people.
After the 2016 National Census, the village of Mahmeleh was elevated to the status of a city.
At the time of the 2006 census, the county's population was 37,978 in 7,025 households. The following census in 2011 counted 41,133 people in 9,121 households. The 2016 census measured the population of the county as 41,359 in 10,708 households.
Khonj County's population history and administrative structure over three consecutive censuses are shown in the following table.