Australia's new Prime Minister is Liberal Party Tony Abbott.

In an open letter to voters released on Sunday, Mr Abbott said:

"Something very significant has happened today. Today the people of Australia have declared the right to government to Australia belongs to you the people of Australia. From today I declare that Australia is under new management. My team will hit the ground running and deliver the stronger Australia and better future that you voted for."

In a meeting with key department chiefs, Martin Parkinson (Treasury), David Tune (Finance) and Ian Watt (Prime Minister and Cabinet), Mr Abbott went about his agendas as new prime minister for Australia.

"There's border security, there's economic security and the people expect, quite rightly, that the incoming government will build a strong and prosperous economy for a safe and secure Australia," Mr Abbott said.

In his concession speech defeated Kevin Rudd wished Mr Abbott well.

"A short time ago I telephoned Tony Abbott to concede defeat at these national elections. As PM of Australia I wish him well now in the high office of PM of this country. Therese and I wish he, Margie and their family well in coping with the stresses and strains of high office that lie ahead. We know a little bit of what that is like. And Therese and I look forward to greeting them at the Lodge early next week in the same gracious manner with which Mr and Mrs Howard welcomed us six years ago. Now I want to speak to Labor people and Labor supporters everywhere across Australia."

"I have been honoured to serve as your prime minister . . . but there comes a time where you know when you have given it your all."The things that unite us are more powerful than the things that divide us, which is why the world marvels at Australia."

Meanwhile, Julia Gillard expressed her support to all the candidates of the Australian Labor Party:

A tough night for Labor. But a spirited fight by Kevin, Albo, George + the whole team. My thoughts are with you all. JG

— Julia Gillard (@JuliaGillard) September 7, 2013

In a recent tweet, Ms Gillard then congratulated Mr Abbott for being the new Prime Minister:

Congrats to Mr Abbott & Mr Truss for leading their parties to victory. I wish them & their teams well. It's always an honour to serve. JG — Julia Gillard (@JuliaGillard) September 7, 2013

The Liberal-National coalition is expected to hold 85 and 93 seats in the 150-seat parliament while labor can still hold 57 seats.