Phoenice Libanensis (Greek: Φοινίκη Λιβανησία, lit. 'Lebanese Phoenicia', also known in Latin as Phoenice Libani, or Phoenice II/Phoenice Secunda), was a province of the Roman Empire, covering the Anti-Lebanon Mountains and the territories to the east, all the way to Palmyra. It was officially created c. 392, when the Roman province of Phoenice was divided into Phoenice proper or Phoenice Paralia, and Phoenice Libanensis, a division that persisted until the region was conquered by the Muslim Arabs in the 630s.

Agapius of Hierapolis used the term “wilderness of Phoenicia” to refer to the steppe between Emesa and Palmyra, in the former province of Lebanese Phoenicia. During the Crusades, William of Tyre and Jacques of Vitry mention Lebanese Phoenicia in its Graeco-Roman borders and limits, undoubtedly based on the administrative and ecclesiastical geographies still known in the Roman Empire. William of Tyre goes on to call Damascus the “metropolis of Little Syria, otherwise called Lebanese Phoenicia”.

Under the Ottoman Empire, the former province of the Lebanese Phoenicia was present only in titles used by local Rûm Christians of the Patriarchate of Antioch and All the East. In the list of episcopal titles, for instance, the Archbishops of Emesa, Baalbek, and Palmyra are “exarchos over the whole of Lebanese Phoenicia”.

The province of Augusta Libanensis, mentioned in the Verona List, was short-lived, but formed the basis of the re-division of Phoenice c. 400 into the Phoenice I or Phoenice Paralia (Greek: Φοινίκη Παραλία, "coastal Phoenice"), and Phoenice II or Phoenice Libanensis (Φοινίκη Λιβανησία), with Tyre and Emesa as their respective capitals. In the Notitia Dignitatum, written shortly after the division, Phoenice I is governed by a consularis, while Libanensis is governed by a praeses, with both provinces under the Diocese of the East. This division remained intact until the Muslim conquest of the Levant in the 630s. Under the Caliphate, most of the two Phoenices came under the province of Damascus, with parts in the south and north going to the provinces of Jordan and Emesa respectively.

Due to mass administrative reforms and edicts directed at Phoenice Libanensis with the goal of preventing further pro-Sassanid raids and invasions, the province was now ruled by two ducēs during the reign of Justinian I.

In the edict dating from c.535–539 of Justinian the Great on the province of Phoenice Libanensis, the emperor demanded that the governor restrain the ‘powerful households’, as he declared that the lawlessness of such regions' magnates made him "feel too embarrassed even to speak of the enormity of these people’s errant behaviour, and of how they have bodyguards protecting them and an intolerable number of people behind them, all committing barefaced banditry." In October 527, Justinian’s reorganization of the military administration of Phoenicia Libanensis began, due to the pro-Sassanid Arab raids on the territory. This was amongst his first acts after taking the Byzantine throne. He added a duke (Latin: dux) to the one already established there, causing the province to have two dukes, although the seat of the new duke isn't mentioned in sources. The emperor also ordered the newly appointed comes Orientis, Patricius, to reconstruct Palmyra, its churches, and its baths, and stationed a numerus and a number of limitane there. On the basis of this and of a passage in Procopius, scholars have concluded that the new dux was stationed in Palmyra.

These reforms were due to the devastating raids that were led by the Lakhmid Al-Mundhir during Justin's reign, such raids have reached deep into Oriens, most especially the invasion as far as Emesa in 527. This raid affecting Lebanese Phoenicia probably inspired Justinian's measures. Justinian had the defense of Jerusalem in mind, expecting the dux in Phoenicia to protect the Holy City. Mundhir's raid as far as the Holy Land must have made the Roman authorities apprehensive about the safety of Palestine, and seeing that Mundir had taken a route from Palmyra to Emesa and Apamea. Byzantium wanted to protect the interior of Oriens by intercepting Mundir at Palmyra to prevent him from penetrating deeper into Roman territory. It also seems that the number of phylarchs (pro-Roman Arab sheikhs) assigned to Phoenicia was also raised to two or more. In the edict on the province of 536, more than one phylarch is referred to. In 528 three Arab phylarchs took part in the punitive expedition against Mundhir, and dukes from Phoenicia also participated. Two of the phylarchs named by John Malalas; Naaman and Jafna, may have been appointed to the newly reorganized province.

Palmyra was the last place Justinian fortified in his enormous building program all over the empire, largely for military reasons, other reasons for such building program in the region may have to do with biblical references, as Malalas refers to the biblical association of Palmyra with Solomon, the Old Testament king whom Justinian claimed to have surpassed in the building of Hagia Sophia. In the mid-530s Justinian initiated a wide-ranging program of administrative reforms in the eastern provinces, which included Phoenicia Libanensis.