The attack, in the Police Lines district follows a surge in violence targeting officers in this restive, northwestern city near the Afghan border.
No group has claimed responsibility.
The rescue operation continues but workers say hope is now dwindling of finding survivors.
Late on Monday (January 30) a mass funeral was held with full police honors for some of the victims.
At least 170 people were wounded in the blast, which demolished the upper storey of the mosque as hundreds of worshippers performed noon prayers.
The site is the main place of worship in the district, which houses offices for the police and counter-terrorism unit.
Authorities say they do not know how the bomber managed to enter the area, which is protected by a series of checkpoints manned by police and military personnel.
Defence minister Khawaja Asif said the bomber was stood at the first row in the prayer hall when he detonated his explosives.
"It is a matter of great concern for us Pakistanis that they (bombers) can enter mosques. So many people were martyred. They were beautiful people, somebody's children, somebody's fathers. Some may have been the sole bread winners of their families. It is a matter of great condemnation that terrorists can enter a government department. If the government departments don't have security, what safety can they provide us?"
Security was noticeably tighter around the city on Tuesday morning.
Peshawar sits on the edge of the Pashtun tribal lands, a region mired in violence for the past two decades.
The most active militant group in the area is the Pakistani Taliban, also called the TTP, an umbrella group for Sunni and sectarian Islamist factions opposed to the government in Islamabad.
The TTP denied responsibility for Monday's bombing, though it has stepped up attacks since withdrawing from a peace deal with the government last year.
