He joined the ‘’Federazione Giovanile Comunista Italiana’’ (Italian Youth Communist Federation) at the age of 15, and was elected Florence city councilor in 1990 as member of the Italian Communist Party, serving until 1995.

He was the Chairman of ANCI, the national association of Italian municipalities (2000-2009), and a member of the Bureau of the Committee of the Regions (2008-2009).

[1] Currently, Leonardo Domenici is an MEP, belonging to the Progressive Alliance of Socialists and Democrats (S&D), where he is member of the Committee on Economic and Monetary Affairs and of the Delegation to the EU-Russia Parliamentary Cooperation Committee.

Since 2011 he is rapporteur for the European Parliament on the credit rating agencies regulation.

[4] In February 2008, Domenici and one of the city assessors of Florence announced intentions to launch a suit against the free online encyclopedia Wikipedia.