He was born in Lercara Friddi, Sicily, on 26 June 1878 as the son of Camillo Finocchiaro Aprile, a liberal politician and several times minister, and the Sicilian noblewoman Giovanna Sartorio.
He officially returned to politics in June 1943, a few days before the landing of the Allies in Sicily, launching in Palermo an appeal with an Action Committee for passive resistance against fascist Italy.
He returned free in 1945 but, in October of the same year, he was arrested again with his right arm Antonino Varvaro and sent to political confinement in Ponza, where he remained until March 1946.
The secretary wanted the movement to take a precise political position, in the case in point on the left, while Finocchiaro Aprile considered it transversal to any ideology.
In the III national congress of Taormina, Varvaro was expelled from the MIS also due to pressure from the "right-wing" fringe (Tasca–Carcaci).