Eslamshahr County (Persian: شهرستان اسلام‌شهر) is in Tehran province, Iran. Its capital is the city of Eslamshahr.

In 2012, Bahramabad Rural District was created in the Central District, and Ahmadabad-e Mostowfi Rural District was separated from it in the formation of Ahmadabad-e Mostowfi District, which was divided into two rural districts, including the new Chichaklu Rural District. In addition, the village of Ahmadabad-e Mostowfi was converted to a city.

At the time of the 2006 National Census, the county's population was 447,192 in 114,009 households. The following census in 2011 counted 485,688 people in 139,408 households. The 2016 census measured the population of the county as 548,620 in 168,288 households.

Eslamshahr County's population history and administrative structure over three consecutive censuses are shown in the following table.

According to the information of the State Meteorological Organization of Iran, the long-term average annual rainfall of Eslamshahr County is around 215 mm

Media related to Eslamshahr County at Wikimedia Commons