On 12 July 1975[2] he was appointed by Pope Paul VI auxiliary bishop of Tripoli and Titular Archbishop of Apamea in Syria dei Maroniti.
[3] Maronite Patriarch of Antioch, Anthony Peter Khoraish, consecrated him bishop on August 23, 1975, supported by the co-consecrators Elie Farah, Archeparch of Cyprus and Bishop Joseph Merhi, MLM, Eparch of Cairo.
After the death of his predecessor Antoine Abed the Archeparchy of Tripoli became vacant.
Joubeir was from 1975 to 1977 Apostolic administrator of Tripoli and received the title of Archbishop "ad personam".
In 1987 he ordained future Archbishop Joseph Soueif of Cyprus to the priesthood.