Tehran's chief prosecutor, Said Mortazavi, said dozens of bandits, robbers, and rapists had been arrested in recent weeks.
Mortazavi said that "12 of these bandits were hanged on Sunday morning" in Tehran.
He added that four other convicts were executed last week.
State television aired footage of the handcuffed convicts just before being hanged.
Iran has one of the highest rates of execution in the world. According to Amnesty International, at least 124 people have been put to death this year.