In August 2015, Kalinić signed a contract with Fiorentina. The fee was reported to be a figure close to €5 million. His Serie A debut came in a 2–0 win over A.C. Milan, and he then scored the first goal against Bologna in a match which also ended 2–0. On 27 September, Kalinić scored a hat-trick away against Internazionale in a 4–1 victory. Due to this win, Fiorentina reached the top of Serie A for the first time since 1998–99. Eight weeks later, he scored twice in a game against Empoli, the double earning Fiorentina a 2–2 draw.