Armenians in Turkey (Turkish: Türkiye Ermenileri; Armenian: Թուրքահայեր or Թրքահայեր, T’urk’ahayer, 'Turkish Armenians'), one of the indigenous peoples of Turkey, have an estimated population of 40,000 to 50,000 today, down from a population of almost 2 million Armenians between the years 1914 and 1921. Today, the overwhelming majority of Turkish Armenians are concentrated in Istanbul. They support their own newspapers, churches and schools, and the majority belong to the Armenian Apostolic faith and a minority of Armenians in Turkey belong to the Armenian Catholic Church, the Armenian Evangelical Church, or are Muslim. They are not considered part of the Armenian diaspora, since they have been living in their historical homeland for more than four thousand years.

Until the Armenian genocide of 1915, most of the Armenian population of Turkey (then the Ottoman Empire) lived in the eastern parts of the country that Armenians call Western Armenia (roughly corresponding to the modern Eastern Anatolia region).

Armenians are one of the four ethnic minorities officially recognized in Turkey, together with Jews, Greeks, and Bulgarians.

In addition to local ethnic Armenians who are Turkish citizens, there are also many recent immigrants from Armenia in Istanbul. There is also an unknown number of officially Muslim citizens of the Republic of Türkiye who have recently started to identify as Armenians based on their Armenian roots, after being Islamised decades or centuries earlier. They are referred as Hidden Armenians or crypto-Armenians.

Armenians living in Turkey today are a remnant of what was once a much larger community that existed for thousands of years, long before the establishment of the Sultanate of Rum. Estimates for the number of Armenian citizens of the Ottoman Empire in the decade before World War I range between 1.3 (official Ottoman data) and 3 million (independent estimates).

When Constantinople finally became part of the Ottoman Empire, financial support was given to the Apostolic Church by the Sultan, so it could build churches in the city, which prior to that the Byzantines refused as they viewed the church as heretical. Armenians in the Ottoman Empire were viewed as a separate millet, and given the status of second-class citizens, but were not usually mistreated until later in the empire's history. Many Armenians gained significant positions in the empire in professions such as banking, which they almost had a monopoly in. The oldest Turkish company, Zildjian, was founded by an Armenian in the 17th century.

Starting in the late 19th century, political instability, dire economic conditions, and continuing ethnic tensions prompted the emigration of as many as 100,000 Armenians to Europe, the Americas and the Middle East. This massive exodus from the Ottoman Empire is what started the modern Armenian diaspora worldwide.

There was conflict between Armenians, Turks and Kurds between 1892 and 1915. The Armenian genocide followed in 1915–1916 until 1918, during which the Ottoman government of the time ordered the deportation. These measures affected an estimated 75–80% of all the Armenians living in the Ottoman Empire during World War I. Many died directly, while others died as a result of dehydration, disease, and starvation during the death marches.^{[citation needed]}