Islamist violence has been on the rise in Pakistan in recent months, undermining Prime Minister Nawaz Sharif's efforts to tame the insurgency by launching peace talks with the Taliban.
Yesterday's blasts happened outside a police station in an area crowded with shops and families. Police said it appeared at least one of the explosions had been a car bomb.
There was no immediate claim of responsibility.
A crowd gathered outside the Lady Reading Hospital in Peshawar, where many of the victims had been taken. Distraught relatives frantically tried to dial mobile phone numbers of those caught up in the blasts but were unable to get through.
Women sobbed as ambulances pulled up with more bodies.
"Who is burning Peshawar, who is burning Peshawar?" screamed one woman in a long headscarf.
Shopowner Sher Gul said he had made repeated trips on his motorbike to bring six people to hospital.
The blasts follow an attack by a Taliban faction on Peshawar's Anglican church last Sunday that killed more than 80 people, the deadliest attack on Christians in predominantly Muslim Pakistan.
The Taliban have repeatedly rejected Pakistan's constitution and have called for the full implementation of Islamic law and for war with India.
Mr Sharif was due to meet Indian counterpart Manmohan Singh on the sidelines of the United Nations General Assembly yesterday.