CAV. PROC. GIOVANNI CORNARO was one of the six sons of the powerful and fabulously wealthy Venetian leader Cav. Proc. Giorgio Cornaro (B-29), brother of Queen Caterina Cornaro (B-31) and founder of the Cornaro della Regina branch of the family. Three of Cav. Proc. Giorgio's sons entered the clergy, two rising to the level of Cardinal and one to Archbishop. Each of the other three sons sired a line of the family that was to sustain the wealth and power of the Cornaro della Regina branch of the family for generations.

Cav. Proc. Giovanni was the progenitor of the S. Polo line. His brothers Proc. Giacomo Cornaro (B-61/F-1) and Sen. Girolamo Cornaro (B-64/H-1) were progenitors of the S. Maurizio and S. Cassiano lines, respectively.

A cavalier and Procurator di S. Marco, Cav. Proc. Giovanni represented Venice as Ambassador to the court of Emperor Maximillian, who honored him with the rank of Count Palatine.

Giovanni was owner of two of Venice's most notable palaces. While awaiting the division of his father's estate among the four surviving brothers, Giovanni acquired from the Lando family the palace on the Grand Canal now known as Ca' Cornaro-Spinelli, frequently described as the first Renaissance palace in Venice.

He then embellished the palace with an atrium designed by Michele Sanmicheli, one of the pioneers of Renaissance architecture in the Veneto, and ceiling panels (now lost) by Giorgio Vasari. In the division of his father's estate with his brothers, Giovanni received the site of the Cornaro palace in Campo S. Polo, which had been destroyed by fire in 1535. Giovanni turned again to Michele Sanmicheli, this time to design a new palace for the site. Ca' Cornaro was constructed there in 1555-64.