The state-run daily Etemad identified the young man only by his first name Javad. Iran Focus has learnt from human rights campaigners that his full name is Javad Shojaee.
Shojaee was accused of stabbing an older man during a skirmish as he was returning from school in the city of Isfahan in March 1997. He was 16 at the time.
Human rights campaigners told Iran Focus that United Nations officials had contacted the Iranian mission in Geneva on Monday and sought the execution be put off.
He was hanged at dawn on Tuesday in a prison in Isfahan.
At least eight other individuals who allegedly committed crimes when they were between 15 to 16 years old are currently on death row in the same prison, activists said.
They include Ahmad Mortazavian, Reza Hejazi, Iman Hashemi, Reza Bikesan, Hamid Bikesan, Behnoud Shojaee, Benyamin Rasouli, and Ali Mahin Torabi.