Gerini is recorded as collaborating with Jacopo di Cione on frescoes for the Guild hall of the Judges and Notaries in Florence in 1366. He is the "Niccolaio Dipintore" who worked with Jacopo di Cione on the altarpiece of the "Coronation of the Virgin" commissioned by the Albizzi family for San Pier Maggiore, Florence in 1370. He was paid 12 golden florins "per disegnare la tavola dell’altare" (for the design of the altarpiece) in November of the same year. In addition to the altarpiece, he designed the elaborate throne canopy, while Jacopo di Cione actually produced the piece.