The 21-year-old has signed a contract until 30 June 2016 with the Reds, arriving from Brazilian first-division club Coritiba FC.
Franca, who has already passed a medical in Lower Saxony, will link up with his new team-mates in training on Tuesday and has been assigned the number 16 shirt.
"With his 6'4" and 88kg frame, Franca has the physical attributes which he uses to great effect in games," said Hannover's sporting director Jörg Schmadtke. "He is a robust kind of player who, in my opinion, will go a long way with us."
South American enthusiasm
"I am looking forward to seeing Franca and I am sure that he will be motivated and very ambitious in seeking his chance with us," added Hannover coach Mirko Slomka. "I have had amazing experiences with South Americans and treasure their determination and enthusiasm. I am convinced that Franca will be no exception."
Franca is the Reds' third new signing this month, joining Johan Djourou and Andre Hoffmann at the club.