Born in Stella (Savona) as the son of a landowner, Alberto, he studied at salesians in Varazze and at "Chiabrera" liceo in Savona.
His philosophy teacher was Adelchi Baratono, a socialist reformist who contributed to his approach to socialism and Ligurian working environments. Pertini graduated in law from Genova university.
He was not an interventist during World War I, but he participated as lieutenant and gained some medals as he fought bravely and courageously. In 1918 he joined the PSU (Unitarian Socialist Party), then he established in Florence where graduated again in political science. There he attended Gaetano Salvemini, Rosselli brothers, Ernesto Rossi. Pertini was beaten by Fascist squads on several occasion, but never lost faith in his ideals.
After Giacomo Matteotti's assassination in Rome, he enhanced his struggle against fascism. In 1926 he was condemmned to internment but he succeeded in hiding. Later he organized and accompanied early promiinent socialist Filippo Turati's escape to France, where Pertini remained up to 1926 working as a masoner. On his return to Italy he was arrested in Pisa and sentenced to ten years of imprisonement.
In 1935 he was interned in Ponza ,an island in tirrenian sea,where he remained up to 1943, suffering from severe disease, never applying for mercy, a month after Mussolini's arrest. Once freed, he dipped in struggle against the Germans, who had invaded Italy in the meantime. Arrested by the Nazis, he was sentenced to death but freed by a partisan blitz.
Meanwhile Mussolini had created the RSI (Italian Social Republic) in Northern Italy, where Nazi oppression was prominent. Pertini went north to organize partisan war as a directive member of PSU.
After April 25, 1945 (the end of the war in Italy) he was elected in "costituente" parliament (the parliament which created the modern Italian constitution). In the postwar era he was a prominent member of the directive board of PSU-PSI and was an elected member of the first parliament of the Italian Republic.
In spite of his feeling toward the Communist party, Pertini was ever jealous of independence of PSU .He criticized any kind of colonialism as well as some kind of corruption in the Italian State and within the socialist party, where kept an independent political position
He was appointend president of Camera dei Deputati (one of the two Chambers of Parliament) in 1968 and in 1978 President of the Italian Republic, the highest office in the Republic. As President he succeeded in regaining the thrust of Italians toward the State and institutions. During the BR terrorism period of anni di piombo (leaden years) Pertini was a strong defender of institutions he represented. His death in Rome left a sad hollow in the heart of the nations.