He was the grandson of Giovanni Giolitti, the well-known liberal statesman of the pre-fascist period who served as Prime Minister of Italy five times.

In the spring of 1943 Giolitti resumed his clandestine activities for the Communist Party, contacting numerous military and political personalities, in order to plan the overthrow of the fascist regime.

He was Minister for the Budget from 1963 to 1964, from 1969 to 1972 and from 1973 to 1974 in the governments led, respectively, by Aldo Moro, Mariano Rumor and Emilio Colombo.

From 1977 to 1985, he was a member of the Executive Commission of the European Economic Community in Brussels, and responsible for Regional Policy.

In 2006, he was awarded the Cavaliere di Gran Croce, the highest honour bestowed by the President of the Italian Republic.