On 22 August 2017, Kalinić joined A.C. Milan on loan with an obligation to purchase for a reported fee of about €25 million. He chose to wear the number 7 shirt, as it was vacant. He made his debut in a 2–1 victory at the San Siro against Cagliari on 27 August, coming on as a substitute in the 78th minute. On 17 September, he scored a brace in his first start for Milan in Serie A against Udinese as Milan won 2–1.