In the Italian Democratic Party is the Head of the Foreign Affairs and International Relations Department.

Graduated in Political Science and International Relations at the University of Florence (1988), Pistelli started his political career in the Christian Democracy (Democrazia Cristiana) as Responsible for the foreign affairs office of the Christian Democrat Youth Movement (1987–1991) becoming, in the following years, Member of the secretariat and directorate (1995–1999) and coordinator of the national secretariat (1999–2001) of the Italian People's Party (Partito Popolare), and member of the executive and official responsible for foreign affairs (2001–2004) of the Democracy is Freedom – The Daisy (La Margherita) party.

In 2004 he is elected as a member of the European Parliament (2004–2008), where he serves both as Head of the Italian Delegation, as the vice-chairman of the Alliance of Liberals and Democrats for Europe and as a member of two Committees (Foreign Affairs and Financial and Economic Affairs).

He is also a member of the Council Italy-United States and of the Board of Editors of East (European and Asian Strategies) and continues to cooperate with a number of progressive think tanks such as Policy Network in London, The Center for American Progress and Brookings Institution in Washington, the Foundation IDEAS in Madrid, the European Council on Foreign Relations.

A journalist since 1991, he publishes regularly in various newspapers on issues related to European and international affairs and on specialized magazines like Aspenia and Limes.