Mahvelat County () is in Razavi Khorasan province, Iran. Its capital is the city of Feyzabad.
The village of Shadmehr was converted to a city in 2009, and likewise the village of Abdolabad in 2024.
At the time of the 2006 National Census, the county's population was 47,068 in 12,268 households. The following census in 2011 counted 48,900 people in 14,226 households. The 2016 census measured the population of the county as 51,409 in 15,844 households.
Mahvelat County's population history and administrative structure over three consecutive censuses are shown in the following table.