Born in Florence, Angelo was elected Bishop of Rapolla in 1375, but in 1383 he was transferred to the see of Florence where he had been preceded by a previous family member many years before, Angelo Acciaioli. He was promoted to the cardinalate on 17 December 1384 by Pope Urban VI. He defended legality of the election of Urban VI and his successors against the claims of the antipopes Clement VII and Benedict XIII. In the Papal conclave, 1389 he was actively working on being elected to the papacy, but an anonymous narrative of the Conclave accuses him of simony (bribery), managing thereby to acquire six votes of the thirteen cardinals in the Conclave.Johannes J. J. Döllinger, Beiträge zur politischen, kirchlichen, und cultur- Geschichte der sechs letzten Jahrhunderte III. Band (Regensburg: Georg Joseph Manz 1882), pp. 361-362: "Conclave, quo Bonifacius IX. papa creatus est".
