Supporters of the treaty - a complex set of institutional changes aimed at making the enlarged EU more efficient - were keen to avoid any new round of referendums on it, after years of negotiations.
Sweden, the incoming holder of the EU presidency, was anxious to move forward over Lisbon, especially as Britain's Conservative Party has pledged to hold a referendum on the treaty if elected to government.
Opponents of the treaty see it as part of a federalist agenda aimed at weakening national sovereignty.
The EU leaders also backed a framework for enhanced oversight of the financial sector, after the UK won key concessions to the plans.
The UK had opposed proposals to give a new oversight body the ability to order national governments to use taxpayer money to bail out failing banks.
"Stronger cross-border supervision is in our interests," Gordon Brown said. "UK taxpayers will be protected. The City of London will stand to benefit from this".
EU plans tougher finance rules
The draft summit conclusions say the European Council - the assembly of EU leaders - "stresses that decisions taken by the European Supervisory Authorities should not impinge in any way on the fiscal responsibilities of member states".
The leaders want the European Commission to deliver detailed proposals for the new supervisory bodies by early autumn, so that the new framework will be in place next year.
In another concession to the UK, a new European Systemic Risk Board will not automatically be chaired by the head of the European Central Bank (ECB).
The ECB will still elect the chair, but the new body will not be controlled by the 16-nation eurozone. The board's job will be to spot any threats to financial stability across the EU.
On Thursday, the leaders unanimously nominated the conservative Jose Manuel Barroso for a second term as EU Commission president.
He had no rival - and even had backing from some centre-left leaders. His nomination now needs the approval of the European Parliament next month.
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