The European Union implemented the accord's requirements to cut greenhouse gas emissions two years ago. But its full provisions, forcing governments also to monitor and report emission levels, have only just come into force in the bloc.
"Now we have adopted all the necessary EU legislation to carry out our commitments under the Kyoto Protocol," EU environment commissioner Margot Wallstroem said.
She pointed out that the EU was implementing Kyoto even though the protocol has not entered force internationally -- primary because the United States, the world's biggest polluter, has refused to ratify it.
The accord's complex ratification rules mean it can only take effect once it has been approved by Russia, which has been dragging its feet.
"As a strong bloc of soon-to-be 25 countries, the European Union has a special responsibility to show global leadership and pave the way for other countries to follow suit," the Swedish commissioner said.
But the EU executive itself has not always been so united over Kyoto.
In January Wallstroem upbraided Spanish EU energy commissioner Loyola de Palacio for "astonishing" comments suggesting that the EU might have to review its commitment to Kyoto.
De Palacio had said that the EU would have to "reconsider" its commitment to slash greenhouse gas emissions if Kyoto failed to get the all-important backing it needs from Russia.
"Loyola should make a distinction between her personal view and the EU view," Wallstroem said at the time. "We lead from the very front. We have to stand firm."