Mohammadshahr
Mohammadshahr 
    Persian: ماهانشهر  | |
|---|---|
| Coordinates: 35°45′12″N 50°54′05″E / 35.75333°N 50.90139°E | |
| Country | Iran | 
| Province | Alborz | 
| County | Karaj | 
| District | Central | 
| Population  (2016)  | |
| • Urban | 119,418 | 
| Time zone | UTC+3:30 (IRST) | 
Mohammadshahr (Persian: ماهانشهر) is a city in the Central District of Karaj County, Alborz province, Iran, serving as the administrative center for Mohammadabad Rural District.