Born in Belluno in 1689, Diziani initially learned his trade in the workshop of Antonio Lazzarini, a local painter, before moving to Venice and completing his studies in the schools of Gregorio Lazzarini and Sebastiano Ricci. In 1717 he accompanied the set designer Alessandro Mauro to Dresden, where he started his career as a scenery painter. He continued to work in this field in Munich, as attested by the depictions of the four parts of the day over four of the doors in the Parade-Schlafzimmer. He returned to Venice in 1720, as documented by the records of the painters’ guild, but left again shortly afterwards for Rome at the service of Cardinal Ottoboni. He spent the rest of his life in Venice apart from one last trip to Bergamo in 1751 to complete the decoration of the ceiling of the church of San Bartolomeo, left unfinished when Mattia Bortoloni died suddenly in Milan. One of the founders of the Venetian Academy of Painting in 1755, he was elected president soon after and served in this capacity from 1760 to 1762 and then from 1766 to 1768. He died in Venice in 1767.