Sir Keir Starmer said the UK was again experiencing the “sunlight of hope” after a Labour landslide put him on course to be the next prime minister.
Tory leader Rishi Sunak conceded defeat after a “sobering” night for his party which saw a record eight Cabinet minister lose their seats.
At a victory rally in central London, Starmer said the country could now “get its future back”.
He told jubilant activists “we did it”, adding: “Change begins now”.
Speaking at his victory speech, Starmer said it “feels good, I have to be honest” as results reached the halfway point.
The Labour leader said: “We did it. You campaigned for it, you fought for it, you voted for it, and now it has arrived: change begins now.
“It feels good, I have to be honest. Four and a half years of work changing the party, this is is what it is for: a changed Labour Party ready to serve our country, ready to restore Britain to the service of working people.
“And across our country, people will be waking up to the news, relief that a weight has been lifted, a burden finally removed from the shoulders of this great nation.
“And now we can look forward, walk into the morning, the sunlight of hope, pale at first but getting stronger through the day, shining once again, on a country with the opportunity after 14 years to get its future back.”
He added: “But a mandate like this comes with a great responsibility. Our task is nothing less than renewing ideas that hold this country together – national renewal, whoever you are, wherever you start in life, if you work hard, if you play by the rules, this country should give you a fair chance to get on.
“It should always respect your contribution and we have to restore that.”
Starmer added in his victory speech: “Alongside that, we have to return politics to public service, show that politics can be a force for good. Make no mistake, that is the great test of politics in this era – the fight for trust is the battle that defines our age.
“It is why we campaigned so hard on demonstrating we’re fit for public service. Service is the precondition for hope. Respect a bond that can unite a country. Together, the values of this changed Labour Party are the guiding principle for a new government – country first, party second.”
