On May 30, 1962, Pope John XXIII appointed Zayek to head the Maronite Apostolic Exarchate (the equivalent in the Eastern Churches of a Vicariate Apostolic) for Maronites in Brazil, the first Maronite bishop to serve outside of the Middle East. He was consecrated bishop at a ceremony held in Dimane, Lebanon, on August 5, 1962, by Mar Paul Peter Meouchi, Maronite Patriarch of Antioch, and his co-consecrators were Peter Sfair, Ordinary Bishop for Maronites in Rome, and Abdallah Nujaim, Eparch of Baalbek. The pope, in appointing him, told him, “What you Maronites have does not pertain to you alone but is part of the treasure of the Catholic Church".
