The former French international left Bayern Munich as a free agent after 12 seasons during which he earned the nickname 'Kaiser Franck', winning nine league titles among his 23 club trophies.
"Football is my life. I still have a special love for football and that's why I absolutely wanted to stay in Europe," the 36-year-old told a press conference in Tuscany.
Ribery has agreed a two-year deal worth four million euros ($4.4 million) a year plus bonuses with the Tuscan club.
"There's a special culture here. People are passionate about football," said the former Galatasary and Marseille player.
"It's a beautiful experience for me to come to Italy to be able to take advantage every day on the pitch and to enjoy myself.
"I had an extraordinary welcome yesterday. To see such passionate people who love football is incredible. It made me think of Marseille so it's obviously special. I like this mentality, it suits me."
Ribery was presented to the public at the Artemio Franchi Stadium on Thursday evening, with his number 7 jersey already on sale in shops in the town.
"I'm very motivated, I'm still hungry. I signed two years to bring my experience and to be decisive, to give something new to this club," he continued.
"It's an ambitious club who want to move towards the top of the table.
"We want to finish in the top five, even in the top three, even if we know it will be difficult."
Fiorentina, now under the ownership of Italian-American media magnate Rocco Commisso, have won the Scudetto just twice in 1956 and 1969.
Ribery pointed out that even if he had played less for Bayern because of a thigh injury last January he had remained very important, notably for young players.
"I like helping them and if I can, I always do, that's my mentality," he said.
"I want to explain to them how to only think about football, to have fun, enjoy oneself.
"I've played at the highest level all my life. I've invested a lot, I've worked a lot. That's the reason why I stayed 12 years at Bayern."
Ribery, who replied to some questions in Italian to applause, said the most difficult part of the negotiations had been finding accommodation.
"I told them the biggest problem was to find me a house," he said. "A big one because I've five children!"
Ribery added that even if he was not ready he would make himself available for the Serie A season opener against Napoli on Saturday.
"I need a little time. I don't know how much. But if the 'Mister' (coach Vincenzo Montella) asks me I'll come. Ten minutes, five minutes, two minutes..."