Voting will take place from July 4 to 22, with ballots airlifted to remote constituencies with assistance from the Australian Defence Force.
PNG's general election is among the world's most challenging, because of difficult terrain, punishing weather conditions, poor transport infrastructure and extreme linguistic and cultural diversity, an independent observer's report on the last poll said.
The Australian National University observer group documented 204 deaths from election-related violence in 2017.
PNG's electoral commission, in its report to parliament, said some electorates had faced election violence, intimidation and fraud in 2017, and there was a significant problem with the electoral roll.
"We have lost too many people to election-related violence," Police Commissioner David Manning said on Monday, the Post Courier newspaper reported.
In Mt Hagen township in the western highlands, supporters of rival political candidates stoned and set fire to each other's vehicles last month, and armoured vehicles arrived on Monday to restore stability, police said.
"As we go to the polls on Monday, I wish to again appeal to candidates, their supporters and the general public to take responsibility and make this a free, fair, safe and corruption-free election," Manning said in a statement.
The two main contenders for prime minister, in the 10th election since independence, are incumbent Prime Minister James Marape of the Pangu Party, and former Prime Minister Peter O'Neill of the People's National Congress Party.
Marape pledged to make PNG "the richest black Christian nation" and "make our nation economically independent", the Post Courier reported on Friday, the last day of campaigning.
Marape became prime minister in 2019 after O'Neill resigned amid unhappiness at the handling of a gas deal in the resource-rich but poverty-stricken country.
O'Neill told voters he had used his time out of government to "reflect on what we can do better".
Australia has donated 3000 helmets and pieces of body armour to assist security for the election, police said in a statement.
The donation in June came after reports China would donate 2000 pieces of body armour during a visit by China's foreign minister in May.
O'Neill criticised any donation of security equipment by China as "improper", amid criticism by Australia and the US of China's security deal with neighbouring Solomon Islands.
