He devoted the first half of his career from 1892 to 1920 to pastoral work, preaching and education in the Italian and Slovenian regions of the Austro-Hungarian Empire.
[1][a] On 25 October 1922, Pope Pius XI named him titular archbishop of Myra and Apostolic Delegate to Latvia, Lithuania, and Estonia.
Of the three Baltic nations, Lithuania had the largest Catholic population and Zecchini chose to live in Kaunas at first but his relationship with the government was always contentious and he left within a year.
[b] After years without meaningful progress in building a relationship with successive Lithuanian governments,[3] he was replaced as Delegate to Lithuania on 10 March 1927 by Lorenzo Schioppa.
On 1 November 1924, Pope Pius XI appointed Zecchini Apostolic Administrator of Estonia, a new ecclesiastical jurisdiction created that day by taking territory from the Diocese of Riga in Latvia.
Without the challenge presented in Lithuania by Polish claims, the Vatican could make a supportive gesture, for example, by raising the status of the Diocese of Riga to an Archdiocese on 25 October 1923.