"By the actions we take, savings are safe", said the PM
Agreements made at the G20 global financial summit in Washington provide a "route map" to economic recovery, Gordon Brown has said.
The prime minister hailed as "historic" the countries' vow to act together to reverse the global economic slump.
Commitments were made to boost growth and reform global financial markets.
But shadow chancellor George Osborne said Mr Brown's attempts to secure a global agreement for a fiscal stimulus package had failed.
The meeting brought together leading industrial powers, such as the US, Japan and Germany, and also emerging market countries such as China, India, Argentina, Brazil and others - representing 85% of the world economy.
Its final communique called on governments to harness tax cuts and spending increases to stimulate the global economy.
'New Bretton Woods'
Mr Brown said: "By the actions we take, savings are safe, people will be able to keep their jobs, they will not lose their homes in all of our countries.
"These are extraordinary times and they require extraordinary measures."
At a final press conference at the British Embassy with Chancellor Alistair Darling, Mr Brown welcomed a G20 commitment to "strive" to draw up a timetable for a new world trade deal by the end of 2008.
In the meantime, the member nations agreed a 12-month moratorium on any new protectionist measures.
The UK will hold the chairmanship of the G20 by the time of its next scheduled summit in the spring 2009, and Mr Brown said that the meeting could take place in London.
The prime minister insisted the world was on the "road to a new Bretton Woods" - the 1944 conference which laid the foundations of the current international financial system, including the IMF and the World Bank.
BBC political editor Nick Robinson said the fact that a series of countries now look likely to implement packages of tax cuts and spending increases would allow Mr Brown to claim the UK is in the lead when it came to dealing with the economic crisis.
But Mr Osborne, who accuses the prime minister of abandoning fiscal responsibility, told BBC One's Andrew Marr Show there was no agreement that countries should borrow without limit.
Of the G20 communique, he said: "It is 3,500 words long, has 21 words on fiscal stimulus and says it should be done where appropriate and provided it is consistent with fiscal sustainability.
"Gordon Brown told us before going to Washington that it was all about getting a global agreement for a fiscal stimulus package. He has not done that."
He said Britain had "the worst budget position in the world" and was borrowing more than any advanced economy which, he argued, was "storing up enormous problems for the future".
But his warning that more borrowing could trigger a run on the pound was described as "partisan talk from the opposition" by Mr Brown.
Mr Darling will outline the UK's plans in the Pre-Budget Report on 24 November.
Mr Brown said this would be "very much in line" with the thinking of President-elect Obama, who did not take part in the talks.
The G20 group of countries consists of 19 leading industrialised and developing countries, as well as the European Union.