Over a successful career lasting more than fifty years, Gaspare Diziani painted frescoes, designed stage scenery, and worked as an art restorer. He was also one of the most prolific draftsmen in Venice in the 1700s. Diziani trained first in Belluno and then Venice, where he joined the workshop of Sebastiano Ricci, who greatly influenced Diziani's development. Diziani quickly became renowned not only for his art but for the rapidity with which he worked. This speed of execution was especially evident in Diziani's oil sketches, where he quickly and confidently applied color.
In 1717, Diziani accepted several commissions in Munich and Dresden and painted decorative panels and theater scenery. He returned to Venice in 1720 and remained there for the rest of his life. From 1748 to 1760, his output was especially prodigious; he painted numerous church altarpieces and fresco decorations for villas and palaces in the city and throughout the Vento. In addition to working in oil and fresco, drawings formed a significant part of Diziani's activity. At the end of his long and distinguished career, Diziani died suddenly in a coffee shop in the Piazza San Marco.