Australia's political leaders are looking to Joe Biden to heal deep divisions in the United States and restore America's standing on the global stage.
Scott Morrison joined other world leaders in congratulating the 46th US president and his deputy Kamala Harris on their inauguration.
"The Australia-US Alliance has never been more important," the prime minister said on Thursday.
"I wish you both every success for your time in office and look forward to working closely with your new administration."
Mr Morrison made particular mention of the US and Australia - "the best of mates" - working together on climate change.
Mr Biden has made it clear climate change will be a key priority of his presidency.
Australian Ambassador to the United States Arthur Sinodinos attended the inauguration in Washington DC.
He believes international relations will be strengthened under the Biden administration.
"There is a change of tone, there is a change of emphasis," Mr Sinodinos told 2GB radio.
"That's going to be very positive to what countries can do together and how we face up to challenges like the rise of China."
Opposition Leader Anthony Albanese also offered his congratulations as Mr Biden entered the White House.
He is hopeful Mr Biden can unite America.
"America is a divided country and the last four years have been characterised by a president who often made decisions based upon Twitter," Mr Albanese told ABC radio.
"We have seen a mishandling of the pandemic in the United States and Joe Biden will have a difficult task ahead."
The Labor leader said after more than four decades in parliament, Mr Biden was perhaps the most experienced president in US history and had a strong team around him.
"The rise of Kamala Harris to the vice presidency - a woman of colour - reflects modern America as does Joe Biden's cabinet," he said.
Mr Albanese is confident the president will lead a good government, tackling the coronavirus pandemic and economic recovery.
"He is determined as well to restore America's role in the world rather than the retreat from global leadership that we've seen in recent years and that's a good thing," he said.
"That's in Australia's interests and it's in the world's interests to have a strong America."
Australian Associated Press