Siminshahr (Persian: سيمين شهر)[a] is a city in, and the capital of, Goldasht District of Gomishan County, Golestan province, Iran.

It was previously the administrative center for Jafarbay-ye Sharqi Rural District until its capital was transferred to the village of Basirabad.

[3] In 2002, the villages of Bonavar (بناور),[b] Qarqi (قارقی), and Katuk (کتوک) merged to form the new city of Siminshahr.

[5] At the time of the 2006 National Census, the city's population was 13,545 in 2,762 households, when it was in the former Gomishan District of Torkaman County.

[3] The 2016 census measured the population of the city as 17,205 people in 4,493 households.