Rezvanshahr County () is in Gilan province, Iran. Its capital is the city of Rezvanshahr.
At the time of the 2006 National Census, the county's population was 64,193 in 16,518 households. The following census in 2011 counted 66,909 people in 19,398 households. The 2016 census measured the population of the county as 69,865 in 22,246 households.
Rezvanshahr County's population history and administrative structure over three consecutive censuses are shown in the following table.