He fought in the Revolution of 1932, in São Paulo's side as a first lieutenant, soon promoted to captain in the Battalion Seven September, participating in the battle "Tunnel Front".

As the historian Hélio Vianna noted, "It was Mr. Paschoal Ranieri Mazzilli the first child of non-Portuguese immigrants to occupy the Presidency of the Republic of Brazil".

On 1 April 1964, after the deposition of Goulart, Mazzilli assumed the presidency for a further two weeks before Humberto de Alencar Castelo Branco took power through indirect elections.

Due to the transitory nature of both administrations and the emergency situation that accompanied his two presidential terms, Mazzilli never played a relevant role in the Brazilian government, except in his conciliatory position, avoiding bloodshed in the 1964 military coup.

[7][8] According to Ranieri's nephew, Brazilian lawyer and law professor Hugo Nigro Mazzilli,[9] his government was important to avoid "bloodshed" in the transition between democracy and dictatorship, and his uncle did not support the coup and faced his presidential moments as a constitutional imposition.