He made his first team debut under manager Nebojša Vignjević on 19 March 2013, coming off the bench as a substitute for Miroslav Vulićević in a 3–0 home win over Donji Srem.

After already establishing his place in the starting lineup, Gaćinović helped Vojvodina win the 2013–14 Serbian Cup in the club's centennial year.

He made his official debut for the club on 28 November 2015, playing the full 90 minutes in a 1–2 away league loss against Mainz 05.

[7] In the first half of the 2022–23 season, Gaćinović emerged as a leading figure in Matías Almeyda's plans, scoring 4 goals and assisting another four.

Following his return in action after the World Cup break and an injury, serbian sources confirmed that Stuttgart expressed interest in his services with an initial 6-month loan and an option to buy for the summer, with AEK Athens denying any negotiation, unless potential offers exceed the sum of €8,000,000.

On 21 September 2023, Gaćinović scored with a low volley after a cross from Ehsan Hajsafi helping to a triumphant 3–2 away win against Brighton & Hove Albion for the first game of the Europa League group stage.