Chief of Army Staff (COAS) General Raheel Sharif had signed their black warrants on Monday.
The terrorists Maulvi Abdus Salam, Hazrat Ali, Mujeeb ur Rehman alias Ali/Najeeb Ullah and Sabeel alias Yahya were involved in APS carnage.
A military court had handed death sentence to all the four terrorists, which was endorsed by the Army Chief.
With the anniversary of the December 16, 2014 attack approaching, the government had also rejected the mercy petitions appealing the executions.
The massacre — in which Taliban gunmen coldly slaughtered more than 150 people, around 132 of them were children, at Army Public School in Peshawar — shocked and outraged a country already scarred by nearly a decade of attacks.
It prompted a crackdown on extremism, with the establishment of military courts and the resumption of capital punishment after a six-year moratorium.
In August, after a trial that took place, the army announced that six militants linked to the assault would be executed, while a seventh was handed a life sentence.
It may be noted here that total number of executions since lifting of moratorium has reached 304.