He served as nuncio to Switzerland. In 1790 the attractive and articulate della Genga attracted favourable attention by a tactful oration commemorative of the late Emperor Joseph II. In 1794 Pope Pius VI made him a canon of Saint Peter's Basilica, and in 1793 created him Titular Archbishop of Tyre. He was consecrated in Rome in 1794 after the appointment and was despatched to Lucerne as the Apostolic Nuncio. In 1794 he was transferred to the nunciature at Cologne, but owing to the war had to make his residence in Augsburg. At this time, he believed it would be his last post and organized the construction of tombs for his mother and for himself.