The future Bishop Ambrose, in the world Peter Cantacuzene, was born on September 3, 1947, in Vevey, Switzerland to Prince Peter Georgievich Cantacuzene and Olga Alekseevna, née Orlova. He is a descendant of the Byzantine royal house. He received his education in the classics and then graduated from the law school at Lausanne University. He subsequently worked as a high school teacher of French and basic jurisprudence. In 1972 he was tonsured a reader in Vevey. In 1974 he participated in the Third All-Diaspora Council.