The attack targeted Shama Cinema on Pajaggi Road, the oldest hall in Peshawar owned by the influential Bilour family.
Police officials said one grenade struck the main door and two more were thrown inside the theatre.
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Rescue officials said 10 people were killed by the explosions. Twenty-two injured were taken to state-run Lady Reading Hospital, they said.
About 60 to 80 people were watching a movie at the hall at the time of the blasts, witnesses said.
Several members of the Bilour family are senior leaders of the secular-leaning Awami National Party. The hall also screens Indian movies.
The cinema owner had been received threatening letters from militants about a possible attack, police said. This was the second such attack on a cinema hall in Peshawar in recent years.
Police officials said a security advisory note was issued to all cinema hall owners to maintain their own security and they had agreed to adopt precautionary measures.
No group claimed responsibility for the attack. Such assaults are usually blamed on the banned Tehrik-e-Taliban Pakistan, which has said music and movies are "un-Islamic".