After destruction, occupancy of the site was forbidden for 25 years. In 122 BC the Roman Senate entrusted Gaius Gracchus and Marcus Fulvius Flaccus with the foundation of a colony on the site of Carthage, Colonia Junonia, which lasted only 30 years.

In 46 BC Julius Caesar visited the site and proclaimed that a city should be built there, populated by a number of landless citizens. This new city flourished and it soon grew prosperous enough to be ranked with Alexandria and Antioch. In 29 BC Augustus centred the administration of the Roman province of Africa at the site. Thereafter it became known as Colonia Julia Carthago, Carthage became a favourite city of the emperors, though none resided there. Of its history during the later empire very little is known, but from the mid-3rd century the city began to decline.

Roman Carthage also became a center of Christianity, being the seat of a bishop from late in the 2nd century. St. Cyprian was bishop there in 248; Tertullian, a Christian ecclesiastical writer, lived and worked in Carthage in the 3rd century; and St. Augustine was bishop of nearby Hippo in the early 5th century. Throughout the 4th and 5th centuries Carthage was troubled by the Donatist and Pelagian controversies. The ancient Phoenician language survived in use as a vernacular in some of the smaller cities of North Africa at least until the time of St Augustine, bishop of Hippo (5th century AD).

Carthage was fortified against barbarian attack in 425. In 439 the Vandal king Gaiseric entered almost unopposed and plundered the city. It remained the Vandal capital until 533, when the Vandal ruler Gaiseric Gelimer, the last Vandal king, was defeated at nearby Decimum by a Byzantine army under Belisarius. Belisarius renaming the city Colonia Justiniana Carthago in honor of the Byzantine emperor Justinian I. Between 697 and 705 the city was captured by the Arabs. In 698 it was again destroyed. Carthage, after its capture by the Arabs in 705, was totally eclipsed by the new town of Tunis.Today Carthage is a wealthy suburb of Tunis.