In his keynote speech to Labour's annual conference in Brighton, Mr Brown said that the party must become "the voice of the mainstream majority" working for "a Britain of aspiration and ambition and opportunity for all ".
And he made clear that his leadership of Labour would deliver a continuation of Tony Blair's "modernisation" agenda, telling delegates " the only future of the Labour Party is as the party of reform".
Mr Brown hailed Tony Blair's achievements in more than a decade as Labour leader.
But he said that, by announcing his plans to step down before the next election, the PM had challenged Labour to "plan ahead" for the post-Blair era.
Without explicitly mentioning his own hopes of stepping into Mr Blair's shoes, the Chancellor spelt out a detailed vision of the Britain he wants to lead.
And he announced plans for a personal tour of the UK over the next year, to discuss his proposals for social, economic and constitutional change.
Repeatedly invoking the Blairite mantra of "New Labour", Mr Brown said he wanted Britain to become "a home-owning, share-owning, asset-owning, wealth-owning democracy, not just for some but for all".
But he also spelt out his ambition to build a sense of community, in comments calculated to please left-wing activists dismayed by his pledge that he will continue Mr Blair's legacy.
Mr Brown said he wanted to see: "Britain no longer defined and diminished by the divisive ideology of them and us, of something for nothing, that denied Britain a shared national purpose and stripped away our sense of community.
"Britain no longer defined and weakened by the centralisation that forgot we are both individuals and neighbours. No longer the 'grab what you can' glorification of everyone for himself, 'no such thing as society' which told people to ask only what they could get for themselves.
"Never again a Britain of them and us, never again the man in Whitehall knows best, but the Britain of we the British people, together.
"A great British society where a new generation of British people can aim as high as they can reach, are empowered to pursue their dreams."
This week's conference has seen the Chancellor effectively anointed as Mr Blair's successor, with a string of Blairite ministers lining up to declare there are no other credible candidates.
Unconfirmed reports this morning suggested that Deputy Prime Minister John Prescott has urged Mr Blair to announce at next autumn's conference that he will hand over to Brown in 2007.
Mr Brown today said: "I believe Tony Blair deserves huge credit not just for winning three elections, but for leading the Labour Party for more than a decade.
"And in the same way he deserves credit for leading us through these difficult and challenging years, he also deserves credit for now asking us and challenging us as a party to begin to plan ahead."
The Chancellor made clear he does not intend to swing Labour to the left as leader, saying that the party must "not just inhabit the centre ground, but dominate it".
"When the Tories tell you the next election will be old Labour versus new Conservatives, tell them the truth," he urged delegates. "The next election must and will be New Labour renewed against a Conservative Party still incapable of renewal.
"When they tell you that at the next election we will abandon reform in Britain, tell them the Labour Party was founded so that by our Labour values we could reform Britain, that the great Labour governments of the last century were great because they were reforming progressive governments that transformed Britain, and that the only future of the Labour Party is as the party of reform."
Mr Brown's comments will dismay trade unions who have regarded him as their best hope of guiding Labour away from the "reform" agenda of increased private sector involvement in the public services.
But the Chancellor insisted that the programme of reform in health, education and other public services was in the best traditions of the party's history.
He concluded: "Our mission - New Labour renewed. Our values - fairness for all, responsibility for all. Our country - united as one moral community.
"A great British society. This we stand for. And this together we can and we will achieve."
Mr Brown took the opportunity to remind delegates of his record of delivering economic growth and stability in his eight years at the Treasury.
Despite his recent admission that he may be forced to downgrade his growth predictions, he said Britain was "unique" in successfully riding out a series of global economic storms.
But he warned the current oil shock, which has seen crude prices reach 70 dollars a barrel, was putting economic stability at risk.
He urged oil producing countries to ease the pressure by pumping more supplies.
"To steer that course of stability, I call on world oil producers and oil companies now to support the British plans agreed this weekend by the whole international community to raise production, to open the books, prevent high prices hurting the poor and ... to promote the environmental agenda for energy efficiency and alternative sources of energy," he said.
In an echo of Mr Blair's famous commitment to "education, education, education", the Chancellor identified Britain's "economic goal now and for the future" as "to become the world's number one power in education".
With the challenge of emerging economies like China and India, Britain could not afford to squander the potential of any of its young people, he said.
It was an "outrage" that Conservative administrations had allowed one child in three to be born into poverty and that teenagers from poor families had only a tenth of the chance of higher education, compared with youngsters from richer backgrounds.
He compared the fight to provide opportunity for all children with the historic struggles to abolish slavery, end child labour, provide universal education and create the NHS.
"When it is asked, centuries from now, who were the people who rid this country of child poverty, who gave every child the best start in life, let it be said it was this Labour Party, this Labour Government, this generation of dedicated men and women who led the way," he said.
Mr Brown carefully gave some comfort to unions upset by his determination to pursue the New Labour programme.
He pledged Labour would deliver on promises made to the unions at the Policy Forum gathering in Warwick last year.
And he expressed determination to legislate on corporate manslaughter and root out gangmasters.
"We will meet our pledge to end the two-tier workforce, in each and every area - including paid holidays - honouring our Warwick commitments," he said.
He hailed emergency workers who helped victims of the July 7 bombings in London as "the quiet heroes of our country" who represented "public service at its best".
But there was a customary warning to unions that he will not allow sympathy for workers to loosen his grip on the purse-strings.
"We must not ever put the goal of full employment at risk by returning to the old days of inflationary pay rises and conflict, the old days of putting sectional interests ahead of the national interest," he said.Reuse content