British Prime Minister Boris Johnson said late on Tuesday that he was looking forward to "working closely" with new US president Joe Biden, who is being inaugurated on Wednesday.
Mr Johnson, who has faced criticism over his close relationship with departing President Donald Trump, said there was a host of policy areas in which he hoped to collaborate with Mr Biden.
"I warmly congratulate Joe Biden on his historic inauguration as 46th President of the United States and look forward to working closely with his new administration as we defeat Covid and build back better from the pandemic," he said.
"In our fight against Covid and across climate change, defence, security and promoting and defending democracy, our goals are the same and our nations will work hand in hand to achieve them."
Britain is set to host a G7 summit in Carbis Bay, south-west England, in June, and the Cop26 UN environmental gathering in Scotland in November.
The G7 summit will be the first face-to-face gathering of the world leaders' forum in almost two years.
Mr Johnson hopes to use the events to bolster his image on the international stage, and place post-Brexit Britain as a leader on several key global issues.
"I look forward to welcoming him to Carbis Bay for the G7 and Glasgow for Cop as we join forces to protect our planet," he said.
"Only through international co-operation can we truly overcome the shared challenges we face."
Britain left the EU last year after nearly five decades of membership, and embarked on an uncertain future outside the bloc's rules and regulations on January 1.
Mr Biden has previously voiced his dismay at the UK move, predicting it would prove a geostrategic error.
He has referred to Mr Johnson as a "physical and emotional clone" of Trump, in a sign the pair may have a more distant relationship than those of past transatlantic leaders.
But Mr Johnson was the first European leader to speak to Mr Biden after his November election victory, and his aides insist it was a warm and constructive conversation.
His press secretary, Allegra Stratton, said on Monday that 2021 represented "a year of global leadership for the UK", which had a more "nimble" foreign policy post-Brexit.
"From G7 to Cop ... Great Britain hopes to emerge as a sustainable, science superpower," Ms Stratton said.
