"The needs are overwhelming and an extraordinary effort is needed by the wider donor community to mobilise significant funding," EU aid commissioner Christos Stylianides said in a statement.
"With our substantial contribution, the European Union -- Commission and the member states -- shoulders its responsibility to alleviate the suffering of the Syrian people."
The money consists of 500 million euros in "humanitarian aid, early recovery and longer-term stabilisation assistance" from the European Commission, the executive branch of the EU, along with further increased pledges from the bloc's 28 countries, the EU said.
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The overall pledge is twice that promised at the 2014 Syria donor conference, it added.
Kuwait's emir earlier announced $500 million for the Syrian crisis, which he called the worst in modern history.
UN chief Ban Ki-moon told the conference that the participants needed to raise a total of $8.4 billion: $5.5 billion for refugees and $2.9 billion for people still inside Syria.