Alfredo Pacini received his philosophical and theological education in the seminary of Lucca. He received on 26 July 1913, the sacrament of Holy Orders, and then worked as a parish pastor and teacher in the Archdiocese of Lucca. In the years 1915-1918 he participated as a chaplain in the First World War. 1924 awarded him by Pope Pius XI. the title of Pontifical secret chamberlain and appointed him secretary of the Apostolic Nunciature in Yugoslavia. From 1933 to 1944 Alfred worked for the Apostolic Nunciature Pacini in Poland, 1944-1946 was a consultant to the Apostolic Nunciature in France.
1946 Pope Pius XII appointed him. Apostolic Nuncio to Haiti and Santo Domingo, as well as Titular Archbishop of Germia. The bishop ordained by Angelo Giuseppe Roncalli Alfredo Pacini, the then Apostolic Nuncio to France and later Pope John XXIII .. From 1949 to 1960 represented Alfredo Pacini as Apostolic Nuncio of the Holy See in Uruguay. In 1960 he was nuncio in Switzerland. He participated in the years 1962 to 1965 at the Second Vatican Council. In 1967 he became Pope Paul VI. as cardinal deacon with the title Diakonia Santi Angeli Custodi a Città Giardino in the College of Cardinals. Cardinal Alfredo Pacini died on 23 December 1967 in Rome and was buried in Campannori.