Garmdarreh is a city located in the Central District of Karaj County within the Alborz province of Iran. It serves as the administrative center for the Garmdarreh Rural District.
The city was established in 2004 following the merger of the village of Garmdarreh with several surrounding villages, including Kuhak, Amirabad, Qaleh-ye Salar Nasriyeh-ye Garmdarreh, Sa'adatiyeh-ye Qadim, and Sa'adatiyeh-ye Now.