According to the "Liber Pontificalis"(the book of the Popes), he is of Greek origin. Elected August 31, he was ordained Bishop of Rome in 257.
Possessing a character of goodness, he solved the discord that had been tormenting the Church during teh reign of Cornelius, Lucius, and Stephen. He established the Roman practice of not re-baptizing heretics.
He effected the movement of the remains of Saint Peter and St. Paul. During the martyrdom of Cyprian he began to pronounce the exclamation, ‘Deo gratias” (Thanks be to God).
A few years after his election the emperor Valarian decreed an edict that obliged all Christians to participate in the national worship of pagan gods and prohibited them from meeting in cemeteries, threatening them with exile or death. In August of 258 the persecution began. The Bishops, priests, and deacons were persecuted to death. Sixtus II was one of the first victims of the edict ("Xistum in cimiterio animadversum sciatis VIII. id. Augusti et cum eo diacones quattuor"—Cipriano, Ep. lxxx).In order to escape the attention of the imperial army, Sixtus joined his people on August 6 in one of the lesser known (Prætextatus),next to the Appian Way. While they were celebrating the Sacred Liturgy he was suddenly arrested by a band of soldiers and decapitated together with four deacons: Januarius, Vincentius, Magnus and Stephanus. Two other deacons, Felicissimus and Agapitus, were executed the same day
He died August 6, 258. The Christians transferred his body to the Papal crypt in the cemetery of Saint Calixstus.
Poco antes de su pontificado el emperador Valerio decretó un edicto que obligaba a los cristianos a 
participar en el culto nacional a los dioses paganos y les prohibía reunirse en los cementerios, amenazándolos con exilio o muerte. En agosto del 258 se recrudeció la persecución. Ver: Testimonio de S.Cipriano. Los obispos, sacerdotes y diáconos eran perseguidos a muerte. Sixto II fue una de las primeras víctimas del edicto ("Xistum in cimiterio animadversum sciatis VIII. id. Augusti et cum eo diacones quattuor"—Cipriano, Ep. lxxx). Para escapar la vigilancia de las fuerzas imperiales, Sixto reunió a su pueblo el 6 de agosto en uno de los cementerios menos conocidos (Prætextatus), junto a la Vía Appia. Mientras celebraba la sagrada liturgia fue de repente arrestado por una banda de soldados y decapitado junto con cuatro de sus diáconos: Januarius, Vincentius, Magnus y Stephanus. Dos otros diáconos, Felicissimus y Agapitus fueron ejecutados el mismo día.
Murió el 6 de agosto, 258. Los cristianos transfirieron su cuerpo a la cripta papal en el cementerio de San Calixto.
