Born in Fabriano (Ancona), Italy in 1877, Fabbri was first sentenced for anarchist activities at the age of 16 in Ancona, and spent many years in and out of Italian prisons. Fabbri was a long time supporter of to the anarchist press in Europe and later South America, including co-editing, with Errico Malatesta, the paper "L'Agitazione". He helped edit the paper "Università popolare" in Milan.Fabbri was a delegate to the International Anarchist Congress held in Amsterdam in 1907. He died in Montevideo, Uruguay in 1935.