Haroun made his Royal Antwerp debut against KSV Roeselare, starting the whole game, in a 1–0 win on 6 January 2017. Since making his debut for the club, he quickly established himself in the starting eleven, playing in the midfield position. However, during a match against KSV Roeselare on 18 February 2017, Haroun suffered a hamstring injury and had to be substituted in the 36th minutes, as they won 2–1. After being sidelined for one match, he made his return to the starting line–up against KSV Roeselare in the first leg play–offs final and set up the club's first goal of the game, in a 3–1 win. In the second leg play–offs final, Haroun started the match and helped the side win 2–1 to gain promotion to the Belgian First Division A next season. At the end of the 2016–17 season, he went on to make nine appearances for the club in all competitions.