This election is a critical one for the Philippines' fragile democracy
Ferdinand "Bongbong" Marcos Jr has some 18 million votes against his rival's 8.5 million, an unofficial tally shows.
If the landslide is confirmed as opinion polls had predicted, the Marcos clan, ousted by a people's revolt 36 years ago, would reclaim power.
His main rival is Leni Robredo, a liberal who is currently the Philippines' vice-president.
The process could take days before a winner is officially announced, as was the case in 2016. But pollsters in this campaign have consistently shown the Marcos heir ahead with a commanding 30-percentage-point lead.
His running mate is Sara Duterte, daughter of the incumbent president, a hardliner who has come to the end of his six-year term in office.
Polls closed at 19:00 local time (11:00 GMT), and counting started immediately - although in some places voting was extended to account for Covid restrictions and voters still queuing.
A high turnout was expected of the nation's eligible 67.5 million voters - with many lining up pre-dawn on Monday to cast their votes at polling booths at schools and community centres.
There have been reports of ballot issues, with some voters at a school in Manila telling the BBC they were having trouble feeding their papers into the counting machines. Others reported that they were told to leave their votes with booth officials.
Comelec Commissioner George Garcia had earlier told the BBC "there will always be allegations of irregularities" but there were no significant breaches so far.
He also said reports of violence were "minimal" and that "the police are in full control of the situation".
Voters queue at the Epifanio Delos Santos Elementary School in Manila
Whoever wins Monday's presidential race will take over from Rodrigo Duterte.
Mr Duterte's government has been condemned for its brutality in cracking down on drugs and crime, though the administration has always rejected allegations of wrongdoing.
Critics also say democratic institutions have come under attack in his presidency, pointing to the shutdown of Philippines' broadcaster ABS-CBN, a channel which - like some other independent media outlets - has angered Mr Duterte in the past.
Filipinos are not only voting on the president but also the vice-president, senators, lower house legislators and thousands of lower-ranking officials across the whole archipelago's 7,600 islands.
Bongbong Marcos, 64, is the son of the late dictator Ferdinand Marcos whose regime lasted 21 years.
On Monday, he and his family - including his mother Imelda - cast their votes at a school polling booth in Batac in the country's north, his family's heartland.
Bongbong Marcos (right) was seen with his mother Imelda (centre) who was dressed in red, her son's campaign colour
Ferdinand Marcos' rule saw him plunge the country into martial law and take control of the country's courts, businesses and media. The army and police arrested and tortured thousands of dissidents and political opponents were murdered.
Marcos, his wife Imelda - infamous for her lavish designer wardrobe - and their cronies plundered an estimated $10bn (£8.1bn) from public funds. Public anger over his regime saw him forced out in the People's Power Revolution of 1986 and he died soon afterwards.
Upon his family's return from exile in the 1990s, Mr Marcos used his family's wealth and connections to resume political ambitions, becoming a province governor, congressman and senator.
When he lost the 2016 vice-presidential race to Ms Robredo, he contested the result - and has vowed that he won't be "cheated" this time around.
His running mate is Sara Duterte, daughter of the incumbent president. The pair have promised to "unify" the nation but they rarely discussed any policies during their election rallies.
Leni Robredo is a former human rights lawyer who has consistently led campaigns against Duterte's drugs violence and gender inequality.
She has vowed to tackle corruption, with her campaign slogan being: "Honest government, a better life for all".
Ms Robredo is a human rights lawyer
Her rallies have drawn significant turnouts recently - particularly among engaged, generally young "Pink Shirt" supporters who launched door-knocking campaigns to win her votes.
The other candidates have trailed Marcos and Robredo in polls. They include boxing champion and national hero Manny Pacquiao who has promised to tackle corruption and poverty, and Manila's city mayor Isko Moreno who has promised more infrastructure spending and a harsher line on China.
Critics say the election has been plagued by rampant misinformation on social media.
"I have described it as a cesspool of disinformation and it just gets worse every election cycle," Richard Heydarian, a politics professor at Polytechnic University of the Philippines told the BBC.
Mr Marcos has denied accusations that he's launched online operations to whitewash his family's history. However, his campaign consistently paints his father's dictatorship as a false "golden period" for the country - despite widespread poverty and an economy heavily indebted to foreign banks.
He has also steered clear of debates or forums where he might have to face independent questioning.
For Ms Robredo, tracker groups have reported an escalation in online campaigns harassing and vilifying her with misogynistic messages.
The Asian Network for Free Elections - a monitor - has found past Philippines votes to be generally free and fair.
-- Courtesy of BBC News