The European Union Observers Mission praised the elections as "very encouraging" and said people appeared "much enthusiastic" about choosing a new leadership, media reports said.
It is the first time since independence in 1947 that any civilian government completed five years in office. The ballot will mark Pakistan's first democratic transition from one elected government to another.
Despite Taliban threats asking people to stay at home, long queues of voters were seen in many places in a country beset with problems ranging from failing economy to unending terror attacks.
The exact number of people who voted was not immediately clear. But officials and reports spoke of a mammoth turnout. Pakistan has 86 million voters.
Voting was held for 269 of the 342 seats of the National Assembly and 728 seats in the assemblies of Punjab, Sindh, Balochistan and Khyber Pakhtunkhwa.
The polling began at 8 a.m. and was to end at 5 p.m. But it was extended by an hour. In Karachi, which saw plenty of trouble, balloting was allowed until 8 p.m.
Both former prime minister Nawaz Sharif and former cricketer Imran Khan, two of the main contenders for power along with the ruling Pakistan Peoples Party (PPP), voiced satisfaction over the turnout.
Sharif, chairman of Pakistan Muslim League-Nawaz (PML-N), said the peaceful election was a "good omen".
Imran Khan, who heads the Pakistan Tehreek-e-Insaf, said people voted "fearlessly" in Punjab, the largest of four provinces, and that turnout in Sindh and Balochistan were satisfactory.
Soon after balloting began, 10 people were killed and 50 injured as a huge explosion tore through a group of voters near a polling station in Karachi.
Balochistan saw five deaths, including four in a clash between supporters of two candidates, Dawn reported.
Election officials admitted Saturday that they failed to hold free and fair polls in the country's largest city of Karachi, where voting was marred by two blasts and other incidents of violence.
The violent run-up to the elections left at least 100 people, including three candidates, dead in terror attacks after the Taliban told Pakistanis to boycott the elections.
The Islamists targeted "secular parties". In an audacious act, gunmen abducted former prime minister Yousuf Raza Gilani's son from a meeting in Multan.
The violence and threats forced most political parties to confine themselves to rely extensively on appeals through the electronic media.
"We want change, we are really fed up with the old faces coming back to power every time and doing nothing for the nation," BBC quoted 74-year-old Abdul Sattar as saying in Islamabad.
Leading Pakistani urged people to vote.
"When good people do not vote, bad people benefit," said Chief Election Commissioner Fakhruddin G. Ebrahim after voting.
President Asif Ali Zardari voted through postal ballot. His son Bilawal Bhutto Zardari could not vote as he was not allowed the same facility. The president's two daughters, Aseefa and Bakhtawar, also voted by post.
The Mohajir Qaumi Movement alleged vote rigging in Karachi.
Geo News reported that the Sunni Ittehad Council and Jamaat-e-Islami would also boycott polls in Karachi. The Jamhoori Wattan Party did so in Balochistan.
Imran Khan's associate Arif Alvi accused MQM of wrongdoing and said his party workers were tortured in many areas of Karachi, state-run Radio Pakistan reported.
More than 600,000 security personnel and soldiers were deployed across the country Saturday.
--IANS (Posted on 11-05-2013)