The Noble Tu'ivakano is Tonga's new Prime Minister after winning with 14 votes in the 26-member parliament.
The other candidate, 'Akilisi Pohiva of the Friendly Islands Democratic Party, won 12 votes.
The Interim Speaker, Lord Tevita Tupou, made the announcement to the House which was carried live on Radio Tonga.
The result was made public after he had returned from informing King George Tupou V who, under the constitution, had to be the first person to be advised of the outcome of the vote.
Lord Tupou informed the House that the King will officially appoint the Prime Minister designate tomorrow.
The House has now been adjourned until this afternoon for the election of the Speaker and his deputy.
Tu'ivakano will replace Dr Feleti Sevele, who had been the first commoner to lead Tonga's government.
The election took place following political reforms that for the first time allowed the people to elect a majority of MPs.