The boat, which was carrying around 35 people, had been heading for the Greek island of Chios when it sank off the coast of Cesme, Izmir province.
The island is one of the most preferred destinations for refugees seeking to enter EU member Greece from Turkey.
Two refugees swam ashore and reported the sinking to the Turkish Coast Guard.
Search-and-rescue boats and helicopters were sent to the area. The bodies of three Syrian refugees were found washed up on a nearby beach.
Izmir, Mugla, Aydin and Canakkale – the four Turkish provinces that face Greek islands in the Aegean and Mediterranean seas – are prime spots for refugees heading for the EU.
At least 3,138 refugees have died crossing the Mediterranean Sea so far this year, according to the International Organization for Migration.
The UN’s refugee agency has said more than 640,000 people arrived in Europe via the Mediterranean so far this year.
