He joined the foreign service in 1882, and was posted to the United States at the critical moment of the Italian lynchings in New Orleans, following the assassination of police chief David Hennessy in 1890.

[3] In October 1895, just before a posting to Brussels, he married Giovanna Maria Colonna (1867-1946), daughter of Edoardo, Prince of Summonte, from a family influential in political and court circles.

Between 1901 and 1903 he was in Berlin, serving as head of mission, where he tried to strengthen the Triple Alliance and criticised the German government for recognising the Treaty of Bardo, whereby France had gained control of Tunisia over Italy.

[1] However, in November 1920, due to strong disagreements with the new Italian foreign minister, Count Carlo Sforza, Imperiali was removed from his post in London, replaced by Baron Giacomo de Martino and mostly excluded from post-war negotiations.

After the Fascists came to power in 1922, Imperiali left his position at the League of Nations in 1923, but began to attend the Senate more regularly, becoming a prominent member of the opposition and an authority in matter of foreign relations.