He plans to visit the Vatican to 'ask for forgiveness' from Pope Francis for insulting him during the election campaign.
His spokesperson said: "The mayor repeatedly said he wants to visit the Vatican, win or lose, not only to pay homage to the Pope but he really needs to explain to the Pope and ask for forgiveness."
Mr Duterte, 71, was previously the mayor of the southern city of Davao, he criticised the Pope for causing traffic jams during his visit to Manila.
He said: "It took us five hours to get from the hotel to the airport. I asked who was coming. They said it was the Pope. I wanted to call him: 'Pope, son of a whore, go home. Don't visit anymore.' "
The overwhelmingly Catholic country goes to the polls on Monday to vote for 18,000 offices, from president to local neighbourhood councillors.
According to The Catholic Herald, Mr Duterte says he will rid the country of criminals within six months of taking office.
In his last campaign speech, he threatened to kill drug dealers, armed robbers and other "loser" criminals.
He added that human rights laws need not be adhered to.
Archbishop Antonio Ledesma of Cagayan de Oro said the archdiocese would honour the election result but said: "We are also asking everyone to be sure that all the rule of law and the constitutional processes are followed.
"Because this is one controversial point that it's still not clear how the president will carry on his promises.
"But we are sure that he has already made statements that he will abide by the rule of law."
The archbishop drew attention to a Human Rights Watch report that reported more than 1,400 killings in Davao City.
He warned against supporting a candidate who espoused the 'culture of death'.
During the campaign, Duterte told bishops' not to criticise his choices.
He has previously been in trouble for 'joking' about an Australian missionary that was raped and murdered in his city.
36-year-old Jacqueline Hamill was killed in 1989.
