Son of the Italian immigrant flutist Alferio Mignone, Francisco was already making his mark upon the musical world of Brazil by the time he was 10 years old, gaining notoriety around his district playing in the choro style.

A pianist and orchestra leader at 13, he had gained some fame composing and playing under the pseudonym of Chico Bororó, keeping these activities separate from his formal music training.

An orchestral piece from his first opera of this early period was premiered in Rio de Janeiro by Richard Strauss conducting the Vienna Philharmonic Orchestra, in 1923.

His solo vocal and piano works of this time earned him particular acclaim for their expression of Brazilian musical styles, such as the choro, the modinha, and the valsas (waltzes) reminiscent of strolling serenaders.

Mignone was capable of writing in a variety of styles and his works of the early 1960s and beyond are noted for their eclecticism; it is difficult to find any other unifying feature.