The bomber attacked the procession at midnight local time in the city of Rawalpindi, located next to the capital, Islamabad.
At least 62 people were wounded by the blast, including six policemen. Eight of the dead and wounded were children.
Police tried to stop and search the bomber as he tried to join the procession, but he ran past them and detonated his explosives, a senior police officer said.
The bomber had grenades and some exploded.
Earlier, two bombs went off within minutes outside a Shi'ite mosque in the southern city of Karachi, killing at least one person and wounding several others.
The bombings came as Shi'ites were observing the holy month of Muharram. Tomorrow Shi'ites will observe the holiest day of the month, Ashoura.