The Bronx was ceded to New York County in two parts, West and East Bronx, in 1874 and 1895, respectively, before establishing what is today called the Bronx County. Later European colonists converted the borough into farmlands. After World War I, the Bronx, which was primarily rural at the time, experienced rapid urbanization.

It was previously part of Westchester County until becoming one of the five independent boroughs of New York in 1898. In April 1912, the parts that were taken over from Westchester County in 1873 became the Bronx County. The Bronx was also the last to be created by the state.

Beginning in the late 1980s, the Bronx witnessed an economic and developmental renaissance that continues today.

The native Siwanoy band of Lenape (also known historically as the Delawares) called the Bronx Ranachqua, while other Native Americans called it Keskeskeck. It was divided by the Aquahung River.

The Bronx got its name from Jonas Bronck, who settled in the area in 1639, even though there is still some dispute about his origins. The use of the definite article is due to the way rivers are referred to. The phrase "visiting the Broncks," referring to the settler's family, is said to have inspired the use of the definite article in the borough's name. Both officially and colloquially, the Bronx is referred to as "The Bronx” with the definite article.