The President signed the order late Wednesday after a furore on leading private news television channel talk shows.
An anti-terrorism court in Karachi last week ordered that Shafqat Hussain, convicted of killing a seven-year-old boy in 2004, be hanged on March 19.
Hussain’s case has triggered outrage from rights campaigners, who complain he did not get a fair trial and was only 15 at the time of the killing.
“The president has postponed the execution of Shafqat Hussain for 30 days,” a presidency official told AFP.
Prison officials in Karachi, where the execution was going to take place at 0030 GMT, confirmed that they had received the orders from Islamabad and had cancelled the scheduled hanging.
Officials declined to say further when asked if the case will be reopened or Shafqat’s birth certificate will be taken into account as an evidence of him being a minor when charged of murder.
Hussain was working as a watchman in the sprawling, violent metropolis of Karachi in 2004 when a seven-year-old boy went missing from the neighbourhood.
A few days later the boy’s family received calls from Hussain’s mobile demanding a ransom of half a million rupees ($8,500 at the time), according to legal papers.
Shafqat Hussain was arrested and during his first interrogation admitted kidnapping and killing Umair, whose body was found in a plastic bag in a stream.
Shafqat Hussain later withdrew his confession, saying he had made it under duress, but the case came before an anti-terrorism court which sentenced him to death.
Shafqat Hussain had been due to face the noose on January 14 but the government halted the execution amid protests about his age, and ordered an investigation.
Reintroducing the death penalty was part of Pakistan’s move to step up the fight against militants since a Taliban massacre at a school in Peshawar in December.
So far 48 convicts have been hanged to death.
The United Nations, the European Union, Amnesty International and Human Rights Watch have called on Pakistan to re-impose its moratorium on the death penalty.
Human rights group Amnesty International estimates that Pakistan has more than 8,000 prisoners on death row, most of whom have exhausted the appeals process.-AFP