More than 20 Europeans including French and Germans were also in the process of being expelled to their countries of origin.
Turkey has criticised Western countries for refusing to repatriate their citizens who left to join the Islamic State group (Isis) in Syria and Iraq, and stripping some of them of their citizenship.
Its interior ministry said it deported an American and a Dane on Monday, while Germany confirmed that one of its citizens had also been expelled.
Copenhagen Police confirmed in a press statement that the Danish citizen was arrested upon arrival at Copenhagen Airport on Monday, adding that he had previously been sentenced to four years in prison in Turkey.
However, there was confusion over the fate of the US citizen, with Greece saying that Turkey had attempted to deport him over their shared land border.
Greek police said they rejected the man and sent him back to Turkey. Images showed him temporarily trapped between the two borders early Monday.
Turkey said seven more Germans would be deported on Thursday, while 11 French citizens, two Irish and at least two additional Germans were also being processed.
The country’s interior minister Suleyman Soylu said last week that Turkey had nearly 1,200 foreign members of Isis in custody, and had captured 287 during its recent operation in northern Syria.
It was not clear whether those being deported were captured in Syria or Turkey.
"There is no need to try to escape from it, we will send them back to you. Deal with them how you want," Soylu said on Friday.
Turkey has lately increased pressure on Europe to take responsibility for the problem.
"Turkey is not a hotel for Daesh members," Soylu said last week, using another acronym for Isis.
The return of jihadists follows Turkey's offensive last month in northern Syria against Kurdish militants who were holding thousands of Isis fighters and their families.
Turkey said it would take control of captured jihadists in areas that it seized from Kurdish groups, but demanded greater assistance from Europe.
It remains unclear, however, whether Turkey will be able to repatriate those who have lost their citizenship.
Although the 1961 New York Convention made it illegal to leave people stateless, several countries, including Britain and France, have not ratified it, and recent cases have triggered prolonged legal battles.
Britain alone has stripped more than 100 people of their citizenship for allegedly joining jihadist groups abroad.
In Denmark, an expedited bill, enabling the immigration minister to revoke the passports of Danes who join foreign militant groups, was passed by parliament in October.
The bill makes it possible for Minister for Immigration and Integration Mattias Tesfaye to strip individuals termed ‘foreign fighters’ (fremmedkrigere) of citizenship without trial.