Niccolò Acciaioli was an Italian politician, son of Acciaiolo, of the Florentine family of Acciaiuoli. The strong ties of the family trading company led him to settle in Naples, where he was in close contact with the Angevin court, so as to receive first the title of knight by King Robert of Anjou, then, in 1348, the prestigious title of Gran Seneschal of the Kingdom of Naples. Among his achievements in the Neapolitan court must be remembered the conquest of the principality of Achaia (1338-1441), which once ceded to the king's nephew, Luigi, rewarded the lordship of Corinth, the promotion of marriage between Giovanna d'Angiò and Luigi di Taranto, the reconquest of the kingdom of Hungary for Luigi di Taranto. After the death of Louis (1362) he worked to protect the queen against the rebellious barons on the throne.
His cousin was Angelo Acciaiuoli senior, bishop of Florence, to whom he wrote a famous letter where he defended himself from some accusations, writing a sort of autobiography, a precious historiographical document of the events of the fourteenth century.
A lover of letters and arts, he was a friend of Francesco Petrarca and Giovanni Boccaccio. The Boccaccio, who dedicated to Niccolò's sister, Andreina, Countess of Altavilla, his work: De mulieribus claris, was his guest in 1362 in his castle in the Parco di Nocera.
He built the magnificent Certosa di Firenze in Galluzzo, near Florence, where he was buried, and where many members of the Acciaiuoli family were buried.