Czech Americans (Czech: Čechoameričané), known in the 19th and early 20th century as Bohemian Americans, are citizens of the United States whose ancestry wholly or partly originates from the Czech lands, a term which refers to the majority of the traditional lands of the Bohemian Crown, namely Bohemia, Moravia and Czech Silesia. These lands over time have been governed by a variety of states, including the Kingdom of Bohemia, the Austrian Empire, Czechoslovakia, and the Czech Republic, also known by its short-form name, Czechia. Germans from the Czech lands who emigrated to the United States are usually identified as German Americans, or, more specifically, as Americans of German Bohemian descent. According to the 2000 U.S. census, there are 1,262,527 Americans of full or partial Czech descent, in addition to 441,403 persons who list their ancestry as Czechoslovak.

The first documented case of the entry of Czechs to the North American shores is of Joachim Gans of Prague, a Bohemian Jewish mining engineer who came to Roanoke, North Carolina in 1585 with an expedition of explorers organized by Sir Walter Raleigh (1552–1618).

Augustine Herman (1621–1686) was the first documented Czech settler. He was a surveyor and draftsman, successful planter and developer of new lands, a merchant, a politician and diplomat, fluent in several languages. After coming to New Amsterdam (present New York), he became one of the most influential people in the Dutch Province, which led to his appointment to the Council of Nine to advise the New Amsterdam Governor Peter Stuyvesant. One of his greatest achievements was his celebrated map of Maryland and Virginia commissioned by Lord Baltimore, which he began working on in earnest after removing to the English Province of Maryland. Lord Baltimore was so pleased with the map that he rewarded Herman with a large estate, named by Herman "Bohemia Manor", and the hereditary title Lord.

Another Bohemian living in New Amsterdam at that time, Frederick Philipse (1626–1720), also became quite famous. He was a successful merchant who eventually became the wealthiest person in the entire Dutch Province. Philipse was originally from Bohemia, from an aristocratic Protestant family who had to flee from their homeland due to popish persecution after the Thirty Years' War.

The first significant wave of Czech colonists was of the Moravian Brethren who began arriving on the American shores in the first half of the 18th century. Moravian Brethren were the followers of the teachings of the Czech religious reformer and martyr Jan Hus (1370–1415), Petr Chelčický and Bishop John Amos Comenius (1592–1670). They were true heirs of the ancient "Unitas fratrum bohemicorum" - Unity of the Brethren, who found a temporary refuge in Herrnhut (Czech: Ochranov) in Lusatia under the patronage of Count Nikolaus Zinzendorf (1700–1760). Because of the worsening political and religious situation in Saxony, the Moravian Brethren, as they began calling themselves, decided to emigrate to North America.

This group started coming in 1735, when they first settled in Savannah, Georgia, and then in Pennsylvania, from which they spread to other states after the American Revolution, especially Ohio. The Moravians established a number of settlements, such as Bethlehem and Lititz in Pennsylvania and Salem in North Carolina. Moravians made great contributions to the growth and development of the United States. Cultural contributions of Moravian Brethren from the Czech lands were distinctly notable in the realm of music. The trumpets and horns used by the Moravians in Georgia are the first evidence of Moravian instrumental music in America.

In 1776, at the time of the Declaration of Independence, more than two thousand Moravian Brethren lived in the colonies. President Thomas Jefferson designated special lands to the missionaries to civilize the Indians and promote Christianity. The free uncultivated land in America encouraged immigration throughout the nineteenth century; most of the immigrants were farmers and settled in the Midwestern states. The first major immigration of Czechs occurred in 1848 when the Czech "Forty Eighters" fled to the United States to escape the political persecution by the Austrian Habsburgs. During the American Civil War, Czechs served in both the Confederate and Union army, but as with most immigrant groups, the majority fought for the Union.

Immigration resumed and reached a peak in 1907, when 13,554 Czechs entered the eastern ports. Unlike previous immigration, new immigrants were predominantly Catholic. Although some of the anticlericalism of the Czechs in Europe came to the United States, Czech Americans are, on the whole, much more likely to be practicing Catholics than Czechs in Europe.