EU leaders have agreed a new "reform treaty" at a summit in Lisbon, British government officials said today.
Mr Brown said: "The reform treaty has now been agreed. The red lines have been secured. The British national interest has been protected.
"It is now time for Europe to move on and devote all our efforts to the issues that matter to the people of Europe - economic growth, jobs, climate change and security."
Shadow Europe minister Mark Francois said: "In the small hours of the night Gordon Brown has agreed the revised EU constitution which potentially transfers massive powers from Britain to the EU.
"He had absolutely no democratic mandate to do this and we will now step up our campaign to secure the referendum which he promised the British people all along."
Foreign Secretary David Miliband continued to resist pressure for a referendum, insisting the treaty represented the death certificate for the constitution.
"The constitution is dead. Last night marked the end of the constitution... there was finally the legal text agreed in all languages which showed very, very clearly that by no measure - by no measure of legal structure, by no measure of legal content and by no measure of political consequence - could this be called a constitution.
"The myths about this treaty that have been propagated - that it will mean the end of our seat on the UN Security Council, that we're no longer going to have the Queen's name inside our passports, that is is the end of Britain - are just myths."
He added: "There are important issues about the legal structure of this treaty, there are important points about the content of the treaty, but the political consequence is important as well and the political consequence is that finally, after six years of a process of institutional navel gazing... it was ended.
"So the consequence of this treaty is that Europe needs to prove that it can make a real difference to people's lives on issues like climate, jobs, migration and terrorism."
Mr Miliband told the BBC Radio 4 Today programme that there was "no case at all for any fundamental shift of power without consulting the British people" but that such a change was not happening.
"I am absolutely clear the job now is to make the institutions work, not to shift power in any direction," he said.
UK Independence Party leader Nigel Farage said there should be a referendum, not just on the treaty but on the whole question of British membership of the EU.
"It is over 30 years since the British people were asked. When they were asked in '75, they were told that we could be part of a European Community that was about free trade and friendship," he told Today.
"Well, here in Lisbon we have agreed a treaty that makes the European Union a country. A country called Europe now exists once this treaty goes through - there is no legal debate or argument about that."
There were now 27 million voters in the UK who had not had a chance to have their say on membership, he said.
He said he thought there was a "very good chance" of such a referendum, he said.
"I suspect the only referendum Gordon Brown would concede is the one on whether we are in or out of the European Union because he will think that's more winnable. He also knows it will split the Conservative Party from top to bottom and we are not frightened of it.
"We are ready to take part in that debate and we want, like Switzerland, to be friendly with the EU, to trade with the EU, but not to be governed by it."Reuse content