Armenian Americans (Armenian: ամերիկահայեր, romanized: amerikahayer) are citizens or residents of the United States who have total or partial Armenian ancestry. They form the second largest community of the Armenian diaspora after Armenians in Russia. The first major wave of Armenian immigration to the United States took place in the late 19th and early 20th centuries. Thousands of Armenians settled in the United States following the Hamidian massacres of the mid-1890s, the Adana massacre of 1909, and the Armenian genocide of 1915–1918 in the Ottoman Empire. Since the 1950s many Armenians from the Middle East (especially from Lebanon, Syria, Iran, Iraq, Egypt, and Turkey) migrated to the United States as a result of political instability in the region. It accelerated in the late 1980s and has continued after the dissolution of the Soviet Union in 1991 due to socio-economic and political reasons. The Los Angeles area has the largest Armenian population in the United States.

The 2020 United States census reported that 519,001 Americans held full or partial Armenian roots either alone or combined with another ancestral origin. Various organizations and media criticize these numbers as an underestimate, proposing 800,000 to 1,500,000 Armenian Americans instead. The highest concentration of Americans of Armenian descent is in the Greater Los Angeles area, where 166,498 people have identified themselves as Armenian to the 2000 census, comprising over 40% of the 385,488 people who identified Armenian origins in the United States at the time. The city of Glendale, in the Los Angeles metropolitan area, is widely thought to be the center of Armenian American life (although many Armenians live in the aptly named "Little Armenia" neighborhood of Los Angeles).

The Armenian American community is the most politically influential community of the Armenian diaspora. Organizations such as Armenian National Committee of America (ANCA) and Armenian Assembly of America advocate for the recognition of the Armenian genocide by the United States government and support stronger Armenia–United States relations. The Armenian General Benevolent Union (AGBU) is known for its financial support and promotion of Armenian culture and Armenian language schools.

The first recorded Armenian to visit North America was Martin the Armenian, from Iran. He was an Iranian Armenian tobacco grower who settled in Jamestown, Virginia, in 1618. In 1653–54, two Armenians from Constantinople were invited to Virginia to raise silk worms. A few other Armenians are recorded as having come to the United States in the 17th and 18th centuries, but most moved as individuals and did not establish communities. By the 1770s, over 70 Armenians had settled in the colonies. The persecution of Christian minorities under the Ottoman Empire and American missionary activities resulted in a small wave of Armenian migration to the United States in the 1830s from Cilicia and Western Armenia. Hatchik (Christopher) Oscanyan, a Constantinople American missionary school student, arrived in America in 1835 to pursue higher education. He later worked for the New York Herald Tribune and became the New York Press Club president. Many Armenians followed him and went to the US for education.

During the Civil War three Armenian doctors—Simeon Minasian, Garabed Galstian, and Baronig Matevosian—worked at military hospitals in Philadelphia. The only Armenian known to have participated in hostilities was Khachadour Paul Garabedian, who enlisted in the Union Navy. A naturalized citizen from Rodosto, Garabedian served aboard the blockade ships USS Geranium and USS Grand Gulf as a Third Assistant Engineer and later an officer from 1864 until his honorable discharge from the Navy in August 1865. Dr. Garabed Vartanian, a graduate of the NYU medical school, served in the Army of the Tennessee's 18th Infantry Regiment.

The number of Armenians rose from 20 in 1854 to around 70 by the 1870s. According to official statistics, 14 Armenians immigrated to the United States in 1878. In the late 1870s, small Armenian communities existed in New York City, Providence, Rhode Island, and Worcester, Massachusetts. By the late 1880s, their number reached 1,500. Many of them were young male students of the American Evangelical Missions spread throughout the Ottoman Empire. About 40% came from the Province of Kharpert. Before 1899, immigrants were not classified by ethnicity, but rather by country of birth, obscuring the ethnic origins of many Armenians. After 1869, however, Armenians from the eastern regions of the Ottoman Empire were registered as "Armenian" in American records. The number of Armenians who migrated to the United States from 1820 to 1898 is estimated to be around 4,000.

Armenians began to arrive in the United States in unprecedented numbers in the late 19th century, most notably after the Hamidian Massacres of 1894–96, and before, during and after the Armenian genocide. Before this mass migration to the United States, the number of Armenians in the country was from 1,500 to 3,000. The New York Times talked of about 10,000 Armenians in the US in 1895.

Over 12,000 Armenians from the Ottoman Empire went to the United States throughout the 1890s. This period witnessed cultural contact between American and Armenian through Armenian nationalist dissident organizations within the Ottoman Empire and intense activity of American missionaries in the region who were sympathetic to the Armenian cause, making the long road of migration somewhat more bearable. With the exception of Fresno, California, which had land suitable for farming, the earliest Armenian immigrants mostly settled in the northeastern industrial centers, such as New York City, Providence, Worcester, and Boston. Armenian emigrants from the Russian Empire were only a minority in emigration from Armenian lands across the Atlantic (about 2,500 moved in 1898–1914), because Armenians were treated relatively better in Russia than in the Ottoman Empire. Once in America, some Armenians organized political parties to serve various causes in America and in the homeland. Turkish Armenian migration rose gradually in the first decade of the 20th century, partly due to the Adana Massacre of 1909, and the Balkan Wars in 1912–1913. Before the start of the World War I, there were already 60,000 Armenians in the United States. As more Armenians fell victim to the genocide and more Armenians were deported, the Armenian American community grew dramatically.^{[verification needed]}