Serafino Mazzolini (9 June 1890 – 23 February 1945) was an Italian lawyer, fascist politician, and journalist.
Mazzolini was born in Arcevia, in the Marche. He founded a nationalist group in Macerata, and soon became editor of the daily newspaper L'Unione. An active Italia irredenta and advocate of Italy's entry into World War I, he was a volunteer soldier in 1915, and was awarded a War Merit Cross.
In 1918, Mazzolini returned to Ancona and was deputy editor of L'Ordine newspaper, interrupting his assignment in order to join Gabriele D'Annunzio as the latter attempted to seize Fiume for an "unredeemed" Italy (1919).
A member of the provincial council in Ancona, he took part in the March on Rome of 1922. In 1923 he joined the Partito Nazionale Fascista (PNF) — becoming one of its leaders in 1924-1925. A deputy secretary for the PNF, he contributed to its Propaganda Office, and represented it in the Italian Chamber of Deputies from 1924 on. In 1926 he was awarded a supervisory position as member of the Grand Council of Fascism.
In quick succession, he renounced all PNF political missions, and returned to journalism for a while, before beginning a career in diplomacy. He became Italy's envoy to Brazil, Uruguay, the British Mandate of Palestine, and Egypt.