Firebrand mayor Rodrigo Duterte is set to become the Philippines' next president as results from the election poured in and a rival conceded defeat.
Early on Tuesday morning, a rolling ballot count by an election commission-accredited watchdog showed Duterte had almost 39 per cent of votes cast. He was more than five million votes ahead of his nearest rival with 90 per cent of votes counted.
Grace Poe, a popular senator, won more than a fifth of the votes counted but conceded defeat to Duterte and said his lead reflected the will of the people.
Duterte's incendiary rhetoric and advocacy of extrajudicial killings to stamp out crime and drugs have alarmed many who hear echoes of the Southeast Asian country's authoritarian past but resonated with voters.
The 71-year-old's truculent defiance of political tradition has drawn comparisons with US Republican presidential candidate Donald Trump, as have his references to his libido.
Duterte made a succession of winding, bellicose and at times comical remarks on television as the votes were being counted, venting over corruption and bad governance, and recounting anecdotes from his 22 years as mayor of Davao city.
He said corrupt officials should "retire, or die" and reiterated his support for the police use of deadly force against criminals.
"If they put up a good fight and refuse to surrender and if you feel your life is in jeopardy, shoot. You have my authority," he told reporters in Davao, wearing a checked shirt and slouched in a chair.
His man-of-the-people demeanour tapped into popular disgust with the political establishment over its failure to tackle poverty and inequality despite several uninterrupted years of robust economic growth.
The election numbers reported by the Parish Pastoral Council for Responsible Voting had, by 5.30am (0730 AEST) on Tuesday, accounted for about 90 per cent of the 54 million registered Filipino voters.
Duterte had 14.9 million votes, with the government's candidate Manuel Roxas second with 8.9 million, followed by Poe with 8.3 million votes.
The PPCRV count is not official but Poe's decision to concede defeat added weight to his presumed victory.