"All member states greenlight early EU ratification of Paris agreement. What some believed impossible is now real," European Union President Donald Tusk said on Twitter.
"Victory!" tweeted French Environment Minister Ségolène Royal.
EU Environment Commissioner Miguel Arias Canete told a news conference that the decision was "historic" and "put behind us any doubts that the EU is ready to join the Paris climate agreement".
With the EU left behind by the world's biggest polluters, the US and China, the environment ministers agreed to bypass the individual ratification by all the bloc's members.
So far seven EU countries, including Germany and France, have ratified the deal.
"Member states will ratify either together with the EU if they have completed their national procedures or as soon as possible thereafter," a statement said.
Portugal and Greece are to do so on 7 October, four more in the middle of the month and seven at the end.
Points to be clarified
Royal admitted that " a certain number of points" have to be clarified, notably Poland's demand to know how the reduction of greenhouse gas emissions will be shared and concerned that the UK's decision to leave the EU will affect quotas.
Some countries are also concerned that the collective ratification has set a precedent that could be invoked in the case of other international treaties.
With India set to ratify the deal on Sunday 2 October and Canada planning to do so soon, the deal, which has to be ratified by at lead 55 countries responsible for at least 55 percent of greenhouse gas emissions, should come into effect by the Marrakesh conference.
Ratification will also allow the EU to play a full part in that meeting's decisions.
The Paris climate change agreement commits countries to keep global warming below 2.0°C above pre-industrial levels.
To read our coverage of the Cop21 climate change deal click here