The verdict was announced at Lahore's Central Jail, reports Dawn news.
The court handed Imran Ali the four death penalties for kidnapping, raping and murdering Zainab, and for committing an act of terrorism.
A separate life sentence, along with 2 million Pakistani rupees ($29,000) fine, was also handed to Ali for sodomy along with a seven-year jail sentence for concealing the body in a garbage heap.
Prosecutor General Ehtesham Qadir said the accused had been given ample chance to defend himself, but he chose to confess his crimes despite being told clearly that any information he divulged would be used against him, Dawn news reported.
Zainab's case had sparked outrage and protests across the country after the minor, who went missing on January 4, was found dead in Kasur city on January 9.
Her case was the 12th such incident to occur within a 10 km radius in the city over a 12-month period.