In return, the E.U. may reward Turkey with more financial assistance, visa-free travel and possible progress in its E.U. membership bid. The deal now heads to the desks of the 28 E.U. leaders, but major practical and legal questions remain.
Czech Prime Minister Bohuslav Sobotka tweeted from inside the meeting today: "Agreement with Turkey approved. All illegal migrants who arrive to Greece from Turkey starting March 20 will be returned!"
"At a time when Turkey is hosting three million, those who are unable to find space for a handful of refugees, who in the middle of Europe keep these innocents in shameful conditions, must first look at themselves," Turkish President Tayyip Erdogan said today.
Erdogan added that Europe was "dancing in a minefield," and it should look internally before telling Turkey what to do.
The United Nations' refugee body, UNHCR, says 143,634 refugees have arrived in Greece from Turkey just this year alone. But many don't have proper asylum paperwork and the resettling process has been painfully slow.
Assuming the E.U. leaders approve today's plan, it's unlikely to stem the flow of refugees crossing the Aegean Sea immediately or bring much-needed relief to Greece, where more than 40,000 refugees are stuck, with no way out.
Slammed up against the Macedonian border is the swollen tent camp in Idomeni, Greece, where it has rained everyday for the past 14 days.
No one knows exactly how many refugees and asylum seekers are camped out but non-governmental organizations estimate about 12,000 people are sleeping in tents amid the ankle-deep mud.
NGOs say thousands of women and children are there alone, and many families have been camped out for up to four weeks. Greek Interior Minister Panagiotis Kouroublis today compared conditions in the camp to a Nazi concentration camp.
"This is a modern day Dachau, the result of the logic of closed borders," he said.
Several people drowned, but after braving the river, no one crossed into Macedonia successfully.
The Macedonian police detained and deported about 700 people; everyone else was forced to cross the river again and walk back to the soggy camp.
“We want a solution, we cannot take it anymore,” one Syrian mother said as she made the long trek back to Idomeni camp.
She draped her rain coat over her baby in her arms. "What did he do to deserve this?" She asked. "I brought him to Europe to go to school, to live a better life."
"After giving up our hearts for Europe, she added, "I will now die in Europe.”
ABC News’ Nasser Atta and Dada Jovanovic contributed to this report.