Declaring himself "humbled," by the victory, Mr Turnbull said he would serve out the Coalition's remaining year in office before calling an election, promised a new economic vision and thanked Mr Abbott for his service.

"The burden of leadership is a very heavy one," Mr Turnbull said, and praised the free trade agreements and success in stopping the boats as "very formidable" achievements of Mr Abbott's government.

Mr Turnbull promised a "thoroughly Liberal" government and new economic vision committed to freedom, the individual and the market.

He also vowed to persuade voters, rather than lecture them.

Mr Turnbull's victory is reminiscent of the coup former prime minister Julia Gillard staged against Kevin Rudd in 2010 and makes the former communications minister Australia's fifth prime minister in just over five years.

Liberal MPs gathered at Parliament House at 9.15pm to decide whether Mr Abbott or Mr Turnbull would lead them to the next election.

Ahead of the ballot, both camps were confident of having the numbers but chief whip Scott Buccholz announced Mr Turnbull had prevailed over Mr Abbott 54-44. One Liberal voted informally and another was absent.