Gilardino arrived at the club from Guangzhou Evergrande earlier this week, having spent just five months in the Chinese Super League where he helped Evergrande win the title.
Speaking at his unveiling on Wednesday, Gilardino said he is keen to work alongside strikers such as Mario Gomez and Khouma Babacar and maintain the club's lofty position.
"I return to Florence with a great sense of enthusiasm. I chose Fiorentina because of the way the team plays football. I’m really pleased to be back for a new challenge in the Viola jersey," he said.
"It's been three years since I left the club and I'm 32 now but I still feel young and am in good physical condition. I had a lot of offers but my preference was to return to Florence. I feel excited and motivated and I’m in great shape.
"I'm delighted that Mario Gomez got his goal and Babacar is an important member of the squad.
"I'd like to take this opportunity to thank the Della Valle family and [coach] Vincenzo Montella for having brought me back to Florence. My dream is to get to 60 goals for the club."
