Asia (Ancient Greek: Ἀσία) was a Roman province covering most of western Asia Minor (Anatolia, Turkey), which was created following the Roman Republic's annexation of the Attalid Kingdom in 133 BC. After the establishment of the Roman Empire by Augustus, it was the most prestigious senatorial province and was governed by a proconsul. That arrangement endured until the province was subdivided in the fourth century AD.

The province was one of the richest of the Empire and was at peace for most of the Imperial period. It contained hundreds of largely self-governing Greek city-states, who competed fiercely with one another for status, through appeals to the Imperial authorities and the cultivation of prestigious cultural institutions such as festival games, religious cults, and oratory.

The province of Asia originally consisted of the territories of Mysia, the Troad, Aeolis, Lydia, Ionia, Caria, and the land corridor through Pisidia to Pamphylia. The Aegean islands, with the exception of Crete, were part of the province of Asia. The western part of Phrygia was added to Asia in 116 BC. Lycaonia was added before 100 BC, while the area around Cibyra was added in 82 BC. The southeast region of Asia province was later reassigned to the province of Cilicia. During the Empire, the province of Asia was bounded by Bithynia to the north, Lycia to the south, and Galatia to the east.

The word "Asia" comes from the Greek word Ἀσία, originally only applied to the eastern shore of the Aegean Sea, which is attested in Mycenaean Greek texts as aswia and probably derives from Assuwa, the name of the region in the Bronze Age. After the Greco-Persian Wars of the early 5th century BC, Greek sources often use it to refer to the whole continent.

The territory was ruled by various Macedonian kingdoms following the conquests of Alexander the Great. In 190 BC, the Romans crushed Antiochus III the Great at the battle of Magnesia. In the subsequent Treaty of Apamea (188 BC), he surrendered the entire territory to the Romans, who placed most of it under the control of the Attalid dynasty based at Pergamum. The western part of Phrygia was given to Mithridates V, King of Pontus, while Caria and Lycia were given to Rhodes.

With no legitimate heir, King Attalus III of Pergamum, having been a close ally of Rome, chose to bequeath his kingdom to Rome. Upon his death in 133 BC, the pretender Eumenes III staged a rebellion. He defeated one of the consuls of 131 BC, Crassus Mucianus. The following year, the consul Marcus Perperna brought the war to a close by defeating Eumenes in the first engagement. He followed up his victory by laying siege to Stratonikeia, whither Eumenes had fled. The town was compelled by famine to surrender and the pretender fell into the consul's hands. Manius Aquillius formally established the region as the province of Asia. The bequest of the Attalid kingdom to Rome presented serious implications for neighbouring territories. It was during this period that the Kingdom of Pontus rose in status under the rule of Mithridates VI. He would prove to be a formidable foe to Rome's success in Asia and beyond.

By 88 BC, Mithridates VI of Pontus had conquered virtually all of Asia. Capitalizing on the hatred of corrupt Roman practices, Mithridates instigated a mass revolt against Rome, ordering the slaughter of all Romans and Italians in the province. Contemporary estimates of casualties ranged from 80,000 up to 150,000.

Three years later, Lucius Cornelius Sulla defeated Mithridates in the First Mithridatic War and in 85 BC reorganized the province into eleven assize districts, each central to a number of smaller, subordinate cities. These assize centers, which developed into the Roman dioceses, included Ephesus, Pergamum - the old Attalid capital, Smyrna, Adramyttium, Cyzicus, Synnada, Apamea, Miletus, and Halicarnassus. The first three cities - Ephesus, Pergamum, and Smyrna - competed to be the dominant city-state in Asia province. Age-old inter-city rivalry continued to inhibit any sort of progress towards provincial unity.