The number of places at refugee reception centres is to be increased by 100,000 in a bid to cope with the migration crisis facing Europe.
The measure forms part of a plan hammered out by European leaders aimed at managing the influx of migrants through the Balkans as winter looms and the weather turns colder.
Greece has committed to opening enough reception centres to house 30,000 refugees by the end of the year, with the United Nations providing a further 20,000 places in the country.
The rest will be created in countries to the north along the route to Germany.
“It cannot be that in the Europe of 2015 people are left to fend for themselves, sleeping in fields.”
The summit also agreed to tighten controls on the Greek-Macedonian border to ensure people trying to cross would be registered.
“We have made very clear that the policy of simply waving people through must be stopped,” Mr Juncker added.
Speaking after the summit, German Chancellor Angela Merkel said: “This is one of the greatest litmus tests that Europe has ever faced.
“Europe has to demonstrate that it is a continent of values and of solidarity.
“We will need to take further steps in order to get through this.”
Slovenian Prime Minister Miro Cerar complained his country was being overwhelmed by the refugees, with some 60,000 arriving in the last 10 days alone, and was not receiving enough help from its EU partners.
Commenting on the handling of the crisis, Mr Cerar said: “This is not the European way.
“Europe is at stake now and if we don’t do all we can together to find a common solution then this is the beginning of the end of the EU.”
Meanwhile, the migrants continue to head west, many aiming for safety in Germany, which has said it is expecting 800,000 asylum seekers by the end of the year.