Keir Starmer has become British prime minister after a Labour landslide which saw former leader Liz Truss and a dozen Tory cabinet members lose their seats.
The Conservative rout saw Rishi Sunak forced out of office and the ex-prime minister announced his intention to quit as Tory leader after the party suffered its worst ever result.
Mr Starmer became Prime Minister after meeting Britain's King Charles at Buckingham Palace following the resignation of Mr Sunak.
He spoke outside Number 10 Downing Street on Friday afternoon.
In a statement, he said: This will take a while but no doubt that the work of change begins immediately.
"I have no doubt that we will rebuild Britain with wealth created in every community.
"Our NHS (will be) back on its feet facing the future, secure borders, safer streets. Everyone treated with dignity and respect at work.
"I invite you all to join this government of service in a mission of national renewal.
"Our work is urgent. And we begin it today."
In a farewell statement in Downing Street, Mr Sunak said: “To the country, I would like to say first and foremost, I am sorry.
“I have given this job my all, but you have sent a clear signal that the government of the United Kingdom must change. And yours is the only judgment that matters.
“I have heard your anger, your disappointment, and I take responsibility for this loss.”
After 648 of the 650 Commons seats had been declared, Labour had a majority of 176.
Labour had 412 seats and the Tories 121.
Mr Sunak said: “Following this result I will step down as party leader – not immediately, but once the formal arrangements for selecting my successor are in place.
“It is important that, after 14 years in government, the Conservative Party rebuilds, but also that it takes up its crucial role in opposition professionally and effectively.”