Samuele Pii graduated in History of European Integration at the Faculty of Political Science at the University of Florence, with a thesis on the work of the European Convention, discussed in 2004. His political commitment began with militancy in the Movimento Federalista Europeo (MFE) and its youth section, the Gioventù Federalista Europea (GFE), in which he held numerous offices, including from 1999 until 2007 that of president. During the Campaign "Per una Costituzione federale europea", he was spokesman for youth delegations during meetings with politicians (Ciampi, Prodi, Delors), and for his work he was appointed "European citizen of the year" in 2000.
In 2002 he was appointed by Valdo Spini to the Youth Convention on the Future of Europe. He participated in numerous youth conventions, he was a speaker at conferences, seminars, promoted by local authorities, by the Observatory on the Future of Europe, by the Altiero Spinelli Institute of Federalist Studies. In 2006 he represented JEF-Italia during the visit of President Napolitano to Ventotene, on the occasion of the commemoration of the twentieth anniversary of Spinelli's death.
He collaborated with schools to spread federalist and pro-European themes, and was a member of the editorial board of the "Dibattito Federalista", journal of the MFE.
Between 2007 and 2009 he held the position of president of JEF-Europe.