The 32-year-old Italy international had been strongly linked with a move away from Genoa, with Guangzhou and Major League Soccer side Toronto FC keen to acquire his services.
Gilardino, who was under contract with Genoa until June 2016, scored 15 goals for I Grifoni in Serie A last season but the former Fiorentina star announced his departure via his Twitter account today.
His tweet read: "To my dearest fans and friends, this morning I have signed a contract with Guangzhou and for me a new adventure begins.
"I really wanted to thank you all for your support throughout these years. I had the opportunity to go to Canada in December but I turned it down because I really dreamed of playing with Gli Azzurri.
"With that dream over, I gave myself the aim of getting to know a new culture, a different football and way of life and I made my choice."
Gilardino, who has scored 170 league goals in his career to be among the top 15 all-time scorers in Serie A, will play again under coach Marcello Lippi.
Lippi, who guided the forward and Italy to win the 2006 FIFA World Cup™ in Germany, has been in charge of the Chinese side since 2012.