Speaking ahead of the domestic cup showpiece, the retired centre-back has chosen to side with his sibling instead of the team he departed on two occasions
The 38-year-old, who played for both teams during his career, opined that his sibling is fully capable of leading his team to victory, but the former Italy international also took time to congratulate the Bianconeri for their Serie A title.
"I have beautiful memories of my time with Juventus: I won two league titles, and I defend those Scudetti. That being said, as a Neapolitan, I am especially rooting for my brother, Paolo," Cannavaro told Tuttosport.
"In recent days we have hardly spoken, and that is a good sign. Paolo did not need advice; he is the captain of Napoli and has proven time and again that he can transmit calmness to his team-mates."
Cannavaro then went on to discuss the key battles that are set to take place on Sunday, and he gave credit to the Bianconeri for the successful season they have had so far.
"Napoli will have to be able to harass the three midfield players of Juventus, [Andrea] Pirlo in particular. I expect a major contribution from Hamsik as he is skilled in both defence and offence," the elder Cannavaro brother explained.
"Juventus deserved the championship. I have been at the club in two different periods, before and after 2006; I know the meaning of this victory. [Coach Antonio] Conte and the guys were great; their season is already extraordinary. A second title will make it memorable."