After exercising the priestly ministry for several months as the curate of St Francis Parish in Piacenza, he was sent to Rome and in July 1944 received his degree 'in utroque iure'.
In Rome he did weekend ministry at Sts Fabian and Venantius Parish and for another two years in the little church of Valcannuta near the Pontifical Brazilian College.
From 1944 to 1946 he studied diplomacy at the Pontifical Ecclesiastical Academy. In those years he carried out his ministry in the parish of San Salvatore in Lauro and later, in the 'Collegium Tarsicii', erected at St Lucy's Church on Via Monte Brianzo.
In 1945 he started working in the First Section of the Secretariat of State (now the Second Section for Relations with States). From 1947 to 1950 he was chaplain to the prisoners in the Roman prison of 'Regina Coeli'.
In the spring of 1963 he was sent on mission to the Government of the Republic of Tunisia, and in Tunis he began negotiations to reach a modus vivendi between the Holy See and the Tunisian Government regarding the legal status of the Catholic Church in Tunisia. The modus vivendi was signed in the spring of 1964.
On 3 April 1965 he was appointed titular Archbishop of Forontoniana - he received episcopal ordination on 9 May of that same year - and Apostolic Delegate for Central Africa (Cameroon, Chad, Congo-Brazzaville, Gabon and the Central African Republic), with residence in Yaoundé. In the following years diplomatic relations were established between the Holy See and Cameroon, Gabon and the Central African Republic.
In May 1969 he was appointed Apostolic Nuncio in Peru, where he stayed until August 1973, when he was recalled to Rome to serve as Apostolic Nuncio with special responsibilities and the mission to have contacts with the Governments of Poland, Hungary, Czechoslovakia, Romania and Bulgaria in order to improve the Catholic Church's situation in those countries.
In July 1974 relations between the Holy See and the Polish Government were formalized, and Archbishop Luigi Poggi was named head of the Holy See's Delegation for permanent working contacts with the Government of Poland.
On 19 April 1986 he was appointed Apostolic Nuncio in Italy. By the Holy Father's decision, from that date the Apostolic Nunciature in Italy has been responsible - as are the other Papal Representations - for studying the documentation relative to the preparation of informative processes concerning possible candidates for the episcopacy and proposals regarding episcopal appointments in Italy. The Apostolic Nunciature in Rome is likewise responsible for studying the documentation regarding proposals for the possible erection, consolidation or alteration of the borders of Italian Dioceses.
In May 1990 and the following July, he celebrated respectively his 25th anniversary of episcopal ordination and 50th anniversary of priesthood.
On 9 April 1992 appointed Pro-Archivist and Pro-Librarian of the Holy Roman Church.
Created and proclaimed Cardinal by John Paul II in the Consistory of 26 November 1994, of the Title of San Lorenzo in Lucina.
Cardinal Luigi Poggi died on 4 May 2010.