Another 100,000 spaces in refugee welcome centres will be created under a deal agreed by European leaders at an emergency summit in Brussels.
The heads of 11 EU states and three non-EU countries met to discuss how to handle growing number of migrants.
More than 9,000 migrants arrived in Greece every day last week, the highest rate so far this year.
Under the deal, Greece will open reception centres with enough room for 30,000 migrants by the end of the year.
The UN's refugee body, the UNHCR, will provide another 20,000 spaces in the same time.
It will also add reception centres with another 50,000 spaces in Balkan countries, which are the most popular routes north for migrants looking to travel north to Germany and Scandinavia.