A native of Monaco, Riberi was consecrated a priest in 1922, and from 1925 he worked as a diplomat for the church. In 1934 he was assigned as Vatican representative to East Africa and consecrated an archbishop. He traveled extensively in East Africa but was unable to return because war broke out in Europe at the time he went to make a report to the pope.
At Christmas time of 1942, he brought greetings from the pope to the American and British troops held in the concentration camp in Italy. On 6 Jul 1946, the Vatican decided to establish an embassy in China. Riberi, appointed consul, arrived in Shanghai on 14 Dec. He presented his credentials to President Jiang Jie Shi (Chiang Kai-shek) in Nanjing on 28 Dec and expressed the hope that Jiang would defeat the Communist Party of China. In 1949, when the People’s Republic of China was established, Riberi remained in Nanjing as an ordinary citizen of Monaco but continued to function privately as the Vatican’s consul and a leader of the Chinese Catholic Church. He implemented Pope Pius XII’s policy toward China forbidding Chinese Catholics to support the new government.
In Mar 1951, when the coadjutor of Nanjing, Li Wei Guang, and priests, nuns, and 793 church members expressed their support of the new government, Riberi sent letters of opposition to bishops in the various dioceses. He was expelled from China in Sep 1952 but stayed in Hong Kong for 13 months. He went to Taiwan in Oct 1953, established diplomatic ties between the Vatican and Taiwan in November, and became the Vatican’s consul to Taiwan with a consulate in Taipei. He left Taiwan in 1959 and became the Vatican’s ambassador to Ireland. In 1967 he was made a cardinal.