With no clear frontrunner and all major candidates polling well below the 50 per cent needed to win outright, a June 7 runoff appears likely.
That could prolong uncertainty in the world's third-largest copper producer at a time of rising crime and intensifying competition for influence between the United States and China.
Voting stations opened at 7am local time, with about 27 million people eligible to vote.
Early in the day, voters in parts of Lima complained that several polling stations had yet to open.
Margarita Sandoval, 35, said she had waited in line for two hours without being able to enter her ballot station in Chorrillos, a southern district of the capital.
"I have to work and I can't vote," Sandoval said.
"These elections are a disaster."
Others said the crowded race had made the decision difficult.
"I only decided who to vote for about a week ago," said 33-year-old shop assistant Benjamin Alcantara.
Since 2018, Peru has cycled through eight presidents, fuelling scepticism that any new administration will last a full five-year term following a dizzying turnover driven by impeachments, corruption scandals and weak governing coalitions that have paralysed decision-making.
"People really despise the current congress," said Martin Cassinelli from the Atlantic Council.
"They recognise them as responsible for the political chaos we've had over the last ten years."
Political distrust has fuelled a crowded field spanning the ideological spectrum, including seasoned politicians, a far-right businessman and a television comedian.
Among the best known is conservative Keiko Fujimori, making her fourth presidential bid after reaching the runoff in all three previous races.
Educated in the US and leader of the powerful Popular Force party in congress, Fujimori has framed herself as a guarantor of order and economic stability, appealing to voters alarmed by surging violent crime.
Her candidacy remains polarising, however, due to her family legacy and past legal troubles.
Ricardo Belmont, a former Lima mayor running for the centre-left Civic Works Party, has shot up into second place after a late rise in support.
He is followed by popular comedian Carlos Alvarez, who is campaigning on a tough-on-crime platform.
Both are considered outsiders who have gained traction by tapping into a broader anti-establishment mood, according to analysts.
On the right, former Lima Mayor Rafael Lopez Aliaga, a wealthy businessman with socially conservative views, has campaigned on an ultra-conservative platform but has seen support fluctuate.
Public insecurity has emerged as the dominant theme of the campaign.
Homicides and extortion have climbed in recent years, driven in part by drug trafficking and illegal mining.
Most leading candidates have proposed expanding the role of the armed forces in internal security.
The election also carries geopolitical implications.
Peru's deepening economic relationship with China -- now its largest trading partner and a major investor in mining and infrastructure -- has raised concerns in Washington, which has stepped up diplomatic and security engagement ahead of the vote.
