The Vandalic War (533–534) was a conflict fought in North Africa between the forces of the Byzantine Empire (also known as the Eastern Roman Empire) and the Germanic Vandal Kingdom. It was the first war of Emperor Justinian I's Renovatio imperii Romanorum, wherein the Byzantines attempted to reassert Roman sovereignty over territory formerly controlled by the Western Roman Empire.

The Vandals occupied Roman North Africa in the early 5th century and established an independent kingdom there. Under their king, Geiseric, the Vandal navy carried out pirate attacks across the Mediterranean, sacked Rome in 455, and defeated a Roman invasion in 468. After Geiseric's death in 477, relations with the Eastern Roman Empire were normalized, although tensions flared up occasionally due to the Vandals' adherence to Arianism and their persecution of the Nicene native population. In 530, a palace coup occurred in Carthage due to a defeat against a local chief of the Frexes tribe Antalas, for which Gelimer blamed Hilderic, and the Vandals overthrew the pro-Roman Hilderic and replaced him with his cousin Gelimer. The Eastern Roman emperor Justinian took this as a pretext to intervene in Vandal affairs, and after securing the eastern frontier with Sassanid Persia in 532, he began preparing an expedition under general Belisarius, whose secretary Procopius wrote the main historical narrative of the war. Justinian took advantage of rebellions in the remote Vandal provinces of Sardinia and Tripolitania. These not only distracted Gelimer from Justinian's preparations but significantly weakened Vandal defenses through the dispatch of the bulk of the Vandal navy and army under Gelimer's brother Tzazo to Sardinia.

The Byzantine expeditionary force set sail from Constantinople in late June 533, and after a sea voyage along the coasts of Greece and southern Italy, landed on the African coast at Caputvada in early September, catching Gelimer completely by surprise. The Vandal king hastily gathered his forces and met the Roman army at the Battle of Ad Decimum, near Carthage, on 13 September. Gelimer's elaborate plan to encircle and destroy the Roman army came close to success, but Belisarius was able to drive the Vandal army to flight and occupy Carthage. Gelimer withdrew to Bulla Regia, where he gathered his remaining strength, including the army of Tzazo, which returned from Sardinia. In December, Gelimer advanced towards Carthage and met the Romans at the Battle of Tricamarum. The battle resulted in a Roman victory and the death of Tzazo. Gelimer fled to a remote mountain fortress, where he was blockaded until he surrendered in the spring.

Belisarius returned to Constantinople with the Vandals' royal treasury and the captive Gelimer to enjoy a triumph, while Africa was formally restored to the imperial rule as the praetorian prefecture of Africa. Imperial control scarcely reached beyond the old Vandal kingdom; however, peace was restored and the Roman government firmly established.

In the course of the gradual decline and dissolution of the Western Roman Empire in the early 5th century, the Germanic tribe of the Vandals, allied with the Alans, had established themselves in the Iberian Peninsula. In 429, the Roman governor of the Diocese of Africa, Bonifacius, who had rebelled against the West Roman emperor Valentinian III (r. 425–455) and was facing an invasion by imperial troops, called upon the Vandalic King Geiseric for aid. Thus, in May 429, Geiseric crossed the straits of Gibraltar with his entire people, reportedly 80,000 in total.

Geiseric's Vandals and Alans, however, had their own plans, and aimed to conquer the African provinces outright. Their possession of Mauretania Caesariensis, Mauretania Sitifensis and most of Numidia was recognized in 435 by the Western Roman court, but this was only a temporary expedient. Warfare soon recommenced, and in October 439, the capital of Africa, Carthage, fell to the Vandals. In 442, another treaty exchanged the provinces hitherto held by the Vandals with the core of the African diocese, the rich provinces of Zeugitana and Byzacena, which the Vandals received no longer as foederati of the Empire, but as their own possessions. These events marked the foundation of the Vandalic Kingdom, as the Vandals made Carthage their capital and settled around it.

Although the Vandals thus gained control of the lucrative African grain trade with Italy, they also launched raids on the coasts of the Mediterranean that ranged as far as the Aegean Sea and culminated in their sack of Rome itself in 455, which allegedly lasted for two weeks. Taking advantage of the chaos that followed Valentinian's death in 455, Geiseric then regained control—albeit rather tenuous—of the Mauretanian provinces, and with his fleet took over Sardinia, Corsica and the Balearic Islands. Sicily barely escaped the same fate through the presence there of Ricimer.

Throughout this period, the Vandals survived several Roman attempts at a counterstrike: the Eastern Roman general Aspar had led an unsuccessful expedition in 431, an expedition assembled by the Western emperor Majorian (r. 457–461) off the coast of Spain in 460 was scattered or captured by the Vandals before it could set sail, and finally, in 468, Geiseric defeated a huge joint expedition by both western and eastern empires under Basiliscus. In the aftermath of this disaster, and following further Vandal raids against the shores of Greece, the eastern emperor Zeno (r. 474–491) concluded a "perpetual peace" with Geiseric (474/476).