Macedonia (Latin: Macedonia; Ancient Greek: Μακεδονία) was a province of ancient Rome, encompassing the territory of the former Antigonid Kingdom of Macedonia, which had been conquered by the Roman Republic in 168 BC at the conclusion of the Third Macedonian War. The province was created in 146 BC, after the Roman general Quintus Caecilius Metellus defeated Andriscus of Macedon, the last self-styled King of Macedonia in the Fourth Macedonian War. The province incorporated the former Kingdom of Macedonia with the addition of Epirus, Thessaly, and parts of Illyria, Paeonia and Thrace.

During the Republican period, the province was of great military significance, as the main bulwark protecting the Aegean region from attacks from the north. The Via Egnatia, which crossed the province from west to east was of great strategic importance, providing the main overland link between Rome and its domains in the Eastern Mediterranean. In this period, campaigns against the Dardani and Scordisci to the north and the Thracians to the east were nearly constant. By the first century BC, the province notionally extended to the Danube.

Macedonia was a central theatre for several campaigns of the civil wars at the end of the Republic, including the Battles of Pharsalus and Philippi. During the Second Triumvirate, it fell within Marc Antony's sphere. Several important Roman military colonies were established in Macedonia in this period. After the province came under the control of Augustus following the Battle of Actium in 30 BC, the northern sections were split off as the provinces of Moesia, Dalmatia and Pannonia, meaning that the province lost much of its military role in defending the Danube border, but it remained important for supply purposes and as a source of military manpower. Until AD 15 and again after AD 44, Macedonia was a senatorial province, governed by a proconsul.

Throughout the Imperial period, Macedonia was a prosperous region with several thriving cities, notably Thessalonica and Philippi. These communities were organised in a similar way to other cities of the Roman Empire and were largely self-governing. Greek was the main language of the region, but Latin was used for official purposes and in the Roman colonies. There were substantial Christian communities in the province by the mid-first century AD.

In late antiquity, the province was split into several smaller units, but the old provincial capital, Thessalonica, became the regional centre for the Balkan region and was briefly an Imperial capital under Licinius. The provincial system gradually faded away, until it was replaced altogether by the theme system in the mid-seventh century AD, but the region continued to form part of the Eastern Roman Empire until the end of the fourteenth century.

The Romans clashed with the Macedonian kingdom in three wars in the early third century BC. After defeating Perseus in the Third Macedonian War, Rome abolished the Macedonian monarchy and divided Macedon into four client republics, called merides, with capitals located at Amphipolis, Thessalonica, Pella, and Pelagonia, which were members of a federal league, the League of the Macedonians. Numismatic evidence indicates that the cult of Roma was introduced at this time, being depicted on coins of Amphipolis, Pella, and Thessalonica in this period. Thessaly had been separated from the Macedonian monarchy already, following the Second Macedonian War and a separate Thessalian League was created with Roman permission in 194 BC, with Zeus Eleutherius ('of Freedom') and Athena Itonia as its patron deities. Its coinage superseded that of the individual Thessalian cities and continued until the end of the first century BC.

The kingdom was briefly reunited in 150 BC by the pretender Andriscus (or 'Pseudo-Philip'), leading to the Fourth Macedonian War. After defeating Andriscus near Pydna in 148 BC, Quintus Caecilius Metellus Macedonicus made Macedonia into Rome's fifth provincia - the first new province since the creation of Hispania Ulterior and Citerior in 197 BC. Surviving sources do not explicitly discuss how or why it was decided to convert the region into a permanent province. A number of factors may have been involved, including increased familiarity with territorial expansion, the proven failure of the previous system to maintain the peace, the desire for a new base from which further military expeditions could be undertaken in order to acquire booty and triumphs, and the desire for further tax revenue. The four republics continued to exist as subdivisions of the province, as did the federal league. The date of the establishment of the province in autumn 148 BC is indicated by the epoch date of the provincial era, but in practice it may have been a gradual process.

At its creation, the province of Macedonia encompassed Macedon itself, Paeonia and parts of Illyria, Thessaly to the south, and Epirus to the west. Notionally, the northern border ran from Lissus on the Adriatic coast, eastwards until it reached the Hebrus river, which formed the eastern border with Thrace. These borders were only loosely defined and dependent on the military competence of the governors, with Cicero claiming that "for the governors of Macedonia, the borders were always the same as those marked by swords and shields." The capital was Thessalonica and the governor held proconsular status.