Gomez has signed for the Viola for €16 million.
"I have contrasting emotions, as I am leaving the strongest team in the world and cannot hide a certain nostalgia," Gomez told the official Bayern channel.
"I love football and wanted to play more, which is why I decided to leave. The contact with Fiorentina started some time ago and I was immediately struck by their very ambitious project.
"I preferred Italy to Spain and Fiorentina really impressed me. The Viola play such great football, I can't wait to start."