Mirzazadeh missed the World Championships in Oslo last month with coronavirus but made a winning return in Belgrade.
Mirzazadeh defeated Armenian wrestler David Ovasapyan 2-1 in the 130kg.
The bronze medals went to Dariusz Attila Vitek of Hungary who beat Delian Hossein Alishahi of Switzerland 3-1 on points, and Russia’s Mikhail Laptev, who overcame Fatih Bozkurt of Turkey 6-0 on points.
The 2021 U-23 World Wrestling Championships are being held from November 1 to 7 in Belgrade, Serbia.