He is a leading member of the Communist Refoundation Party (Partito della Rifondazione Comunista; PRC), and served as Minister of Social Solidarity from 2006 to 2008 as part of the Prodi II Cabinet.

A former FIAT worker, his political commitment began at the age of 17, when he joined Proletarian Democracy (Democrazia Proletaria; DP).

He served as a Turin city councillor from 1993 to 1997, shortly after the DP was absorbed by the PRC.

Prior to being appointed to Prime Minister Romano Prodi's Cabinet in 2006, he was responsible for the PRC's social, economic and labour department, with a particular focus on social policy, national civil service, non-EU immigrants and drug-related policies.

On 27 July 2008, Ferrero was elected secretary of the PRC, defeating the other major candidate, Nichi Vendola.