Rocco was born in Montpellier, in Provence (south of France) in an unspecified year between 1348 and 1350. At the time of birth Rocco has a cross-shaped birthmark on his chest, which will allow the body to be recognized after death. The family, the Delacroix, is among the most affluent of the city. In Montepellier, at the local and ancient Rocco University he would study medicine interrupting his studies at the death of his parents, Giovanni and Libera. After the fatal event, the young man distributes his belongings to the poor and leaves on a pilgrimage to Rome. At the time of beginning the pilgrimage he has already taken on the habit of the Franciscan Third Order. Rocco, according to tradition, would have known the terrible scourge of the plague already in his hometown. It arrives in Italy at the moment of maximum virulence of an epidemic of black plague and interrupts the journey to Rome to Acquapendente (Viterbo) where in the litter of S. Gregorio assists plague and sick.
Here the miraculous virtues of the Saint are manifested: the sign of the cross practiced by Rocco on the forehead of the sick provides healing and thus spreads the fame of the miracles of the young French pilgrim. He arrived in Rome between 1367 and 1368. He stayed there for three years, assisting the sick. With the sign of the indelible cross on his forehead, he heals a cardinal who leads him to the presence of Pope Urban V. After leaving Rome, Rocco is in Rimini, Forlì, Caorso and Cesena where he works for plague victims. In Piacenza he contracted the plague and retired into a cave, still existing and transformed into a sanctuary, along the river Trebbia near Sarmato. A dog provides for the sustenance of the Saint with a loaf of bread which he takes from the master's table, the Lord of Sarmato, Gottardo Pollastrelli. He follows the little beast, discovers the cave and takes care of the young man who refuses to follow him to the palace. Gottardo tries in vain to follow Rocco who causes him to desist from the purpose.
Gottardo spreads the life and fame of the miracles; it is believed to have been the first hagiographer of the Saint and the first to have portrayed him in an image and following the teachings of the master he would also have achieved holiness. Among the historians, however, the existence or not of this figure next to the Saint is quite controversial. In the cave to the Saint appears an angel who announces the healing and the faculty to ask a favor to the Lord. On the way back to Montpellier, Rocco is incarcerated as a spy in Voghera. It refuses to reveal itself despite the Lords of the place being maternal. He remains in prison for almost five years. Once again, he receives the apparition of the Angel announcing his near death that arrives in the night between August 15th and 16th probably of 1379. At the moment of the burial, thanks to the sign of the cross that Rocco wears on his chest, his uncle maternal Bartolomeo, Lord of the place where the Saint was imprisoned, recognizes his nephew in the mysterious young pilgrim who never wanted to reveal his identity. Always at the time of burial, the grace that Rocco had asked the Lord will manifest itself with the discovery of the tablet that bears the phrase "Who will call upon my servant will be healed", and which appears in numerous representations of the Saint. The body of S. Rocco will remain in Voghera until 1483 when it will be moved to Venice where a church dedicated to the Saint is erected with an altar that preserves its main remains. The church is officiated by the famous "Archconfraternity of the Scuola Grande di S. Rocco" which still today is the fulcrum of the spread of the cult of S. Rocco all over the world.