Khizar Hayat, a 55-year-old former police officer, was sentenced to death in 2003 for shooting a colleague.
The United Nations has previously called on Pakistan to protect mentally ill inmates, singling out Hayat as having "psychosocial disabilities".
The Justice Project Pakistan (JPP), which is managing his case, said Hayat's lawyer in September 2015 had challenged the execution in light of his mental illness. However Lahore jail authorities pressed ahead with seeking the death warrant which was granted by a sessions court earlier this week.
According the JPP, the judge Shahid Hameed Dar said it would be "unjust" to proceed on Hayat's case without waiting for the Supreme Court's decision in Imdad Ali's case, another mentally-ill man, who was given a last-minute reprieve from execution by the high court in October.
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A final decision on his fate remains pending.
JPP spokesman Waseem Waheed hailed the reprieve, but urged the Supreme Court to set standards for mentally ill prisoners.
"We are relieved to hear that Khizar has been granted a temporary reprieve by the Honourable Court," Waheed said.
Since lifting its moratorium on executions in December 2014, Pakistan has hanged some 420 prisoners, overtaking Saudi Arabia to become the world's third largest executioner nation after China and Iran.
But according to a report by British charity Reprieve, 94 percent of Pakistan's executions have been for non-terrorism offences, despite the government's claim that capital punishment was reinstated to combat Islamist militancy.