Graduated in Political Science at Luiss University in 1982 with a thesis on international negotiation techniques, Belloni embarked on a diplomatic career in 1985.

[1] She has held positions in Italian embassies and representations permanent offices in Vienna and Bratislava, as well as in the Directorates General of the Ministry of Foreign Affairs.

After returning to Rome, she worked briefly in the Russia Office before being promoted in 2000 to the secretariat of the Directorate for European Countries.

In February 2014, she was promoted to rank ambassador; since June 2015, she has held the position of Chief of Staff of the Minister of Foreign Affairs Paolo Gentiloni.

In May 2018, her name was presented by the press, together with the economist Lucrezia Reichlin, as a possible candidate to receive the mandate of Prime Minister of the 18th legislature.