Kuhsar District () is in Salmas County, West Azerbaijan province, Iran. Its capital is the village of Katban.
At the time of the 2006 National Census, the district's population was 30,452 in 5,324 households. The following census in 2011 counted 26,952 people in 5,407 households. The 2016 census measured the population of the district as 27,916 inhabitants in 6,299 households.