The territory was inhabited in the Neolithic, over 4,000 years BC, by the Nuragic civilization. In the 9th century BC the Phoenicians had in Alghero an important port, then under the Romans it semms to have lost importance. In the 11th century AD the Doria family of Geona founded the medieval borough, and because of its strategic position the town was repeatedly attacked in the following centuries, until in 1353 was conquered by the Aragonese led by Catalan Pedro IV. In the late 15th century it was under the rule of Eleonora of Arborea and her husband Brancaleone Doria. In 1720 finally it was included in the Kingdom of Sardinia, under Savoy rule.
At the time of the Aragonese domination, a Catalan community moved to the place in the year 1354, leaving a depep mark in the culture, language and architecture of the town. Catalan was replaced as the official language by Spanish in the 17th century, then by Italian. In the 1990s about 60% of locals still understood spoken Algherese Catalan.