All but two of the EU's 27 leaders have signed a new treaty to enforce budget discipline within the bloc.
The "fiscal compact" aims to prevent the 17 eurozone states running up huge debts like those which sparked the Greek, Irish and Portuguese bailouts.
To take effect, the pact must be ratified by 12 eurozone states.
UK Prime Minister David Cameron, who with the Czechs refused to sign, said the summit had accepted his ideas for cutting red tape and boosting growth.
On Thursday he had complained that his ideas, contained in a joint letter signed by 12 EU leaders, were being ignored.
But after the talks he said "our letter really did become the agenda for this meeting... We now have a plan that we must stick to in the months ahead".
The newly reappointed President of the European Council, Herman Van Rompuy, said the British proposals were being taken seriously and he had sought to redraft the summit's conclusions accordingly.
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Fiscal compact
Critics argue that the fiscal treaty is mainly a political gesture aimed at reassuring taxpayers in Germany, the eurozone's dominant economy, where there is reluctance to pay for further eurozone bailouts.
German Chancellor Angela Merkel described it as a "great leap", a first step towards stability and political union.
Germany is reluctant to increase the size of the permanent rescue fund, the European Stability Mechanism (ESM), which comes into force on 1 July.
The leaders put off until the end of March a decision on its size. There are calls to combine the 250bn euros (£209bn; $333bn) left in the temporary bailout fund - the EFSF - with the 500bn-euro ESM.