Spinelli was born in Rome, and joined the Italian Communist Party (PCI) at an early age in order to oppose the regime of Benito Mussolini's National Fascist Party.
Spinelli sündis Roomas ja liitus nooruses Itaalia Kommunistliku Parteiga, et vastanduda Benito Mussolini Rahvuslikule Fašistlikule Parteile.