The count of Barcelona (Catalan: comte de Barcelona, Spanish: conde de Barcelona, French: comte de Barcelone, Latin: comes Barcinonensis) was the ruler of the County of Barcelona and also, by extension and according with the Usages and Catalan constitutions, of the Principality of Catalonia as prince (sovereign) for much of Catalan history, from the 9th century until the 18th century. After 1162, with Alfonso II of Aragon and I of Barcelona, the title of count of Barcelona was united with that of king of Aragon, and after the 16th century, with that of king of Spain.

The Emperor Charlemagne conquered the area north of the river Ebro and captured the city of Barcelona in 801. He then organized these lands, historiographically known as the Marca Hispanica, into various counties, one of which was the County of Barcelona, with the city of Barcelona as its capital. The Count of Barcelona, usually holding other counties simultaneously, eventually obtained primacy over the region. As the County became hereditary in one family, the bond of the Counts to their Frankish overlords loosened, especially after the Capetian dynasty supplanted the Carolingians.

In 1150, Count Raymond Berengar IV married Queen Petronilla of Aragon. Their son Alfonso succeeded as Count and also as King of Aragon, establishing the Crown of Aragon. In the Treaty of Corbeil (1258), King Louis IX of France relinquished France's historical claim to the County. In 1516, Queen Joanna of Castile also succeeded in Catalonia and Aragon, forming the Monarchy of Spain. The title of Count of Barcelona remained one of the many hereditary titles of the Spanish monarchy.

In the 20th century, the title regained some prominence when Juan de Borbón, the exiled heir to the Spanish throne, adopted the title of Count of Barcelona. In doing so, he claimed a historical royal title without claiming to be the current king of Spain, especially after his son Juan Carlos became the prospective successor of the then-ruler of Spain, Francisco Franco. In 1977, after Juan Carlos had become king upon Franco's death in 1975, he officially awarded the comital title to his father, who had renounced his rights to the throne. Juan held that title until his death in 1993, when it reverted to Juan Carlos. Juan de Borbón's widow used the title Countess of Barcelona until her death in 2000.

During this period, the County of Barcelona was one of many Counties at the March located in the Eastern Pyrenees and known as Gothia or Marca Hispanica. The Counts of this March were appointed by the Carolingian authorities.

The crisis of the Carolingian Empire, incapable of attending to the requests for help against the Moorish attacks coming from the Catalan counts, resulted in a disconnection between them and the Carolingian central power far North. The County of Barcelona became a hereditary title.

The succession of Ramon Berenguer IV and Petronilla led to the creation of the Crown of Aragon.

Martin died without legitimate descendants (interregnum 31 May 1410 – 24 June 1412). By the Compromise of Caspe of 1412 the County of Barcelona and the rest of the dominions of the Crown of Aragon passed to a branch of the House of Trastamara.