The leader of the People's National Congress Party was nominated by Abau MP, Sir Puka Temu.
O'Neill was returned to the PM’s post with 60-46 votes.
Parliament is now in recess as the PM-elect will go to Government House for Governor-General Sir Bob Dadae to swear him into office.
Speaker Job Pomat invited the People's National Congress Party, on advice of the Governor-General, to nominate a person for the Prime Minister's position.
Pomat said the decision is in line with the Organic Law of Integrity of Political Parties and Candidates because PNC Party won the highest number of seats in the 2017 National Elections.
(Loop file pic)