The bomber, who blew himself up among groups on Tuesday near Istanbul's most popular tourist attractions, had entered Turkey as a refugee from Syria.
Turkey's Prime Minister has called on the world to show solidarity with Turkey, as it did for Paris, following the attack.
The explosion struck in the heart of the tourist district Sultanahmet, near the famous Blue Mosque.
A witness says there was confusion immediately after the blast.
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"There was an explosion and we were all afraid, we were trying to cover ourselves. After the first shot we checked the square and there was people lying on the ground..."
German Chancellor Angela Merkel says she is saddened to think those who had travelled to Istanbul would not make it home
"I'd like to say to the families of the victims - you are not alone. We stand with you, with a lot of strength, We also wish to the wounded that they recover very quickly."
Turkish President Recep Tayyip Erdogan has condemned the attack.
"I strongly condemn this attack - this apparent terrorist act caused by a suicide bomber. I'd like to offer my condolences to those who lost their loved ones and pray for those who lost their lives. Once again this shows us how important it is to be united in the face of terrorism. Turkey's determined resolute stance against terrorism will continue."
