In the 2018–19 season, Haroun continued to establish himself in the starting eleven, playing in the midfield position, as well as, captain. It wasn't until on 19 August 2018 when he scored his first goal of the season, in a 1–1 draw against Club Brugge. A month later, Haroun signed a contract extension with the club, keeping him until 2020. Two days later on 16 September 2018, he scored his second goal of the season, in a 5–1 win against Zulte Waregem. Haroun scored his third goal of the season, in a 2–2 draw against Gent. He later added two more goals throughout October, scoring against Lokeren and Waasland-Beveren. Since the start of the 2018–19 season, Haroun started in every matches until he was suspended for one match. After serving a one match suspension, Haroun returned to starting line–up, in a 3–1 loss against Sint-Truidense on 2 December 2018. However, his return was short–lived when he suffered a quadriceps injury. But Haroun made his return to the starting line–up, in a 2–0 loss against Waasland-Beveren on 15 December 2018. However, he suffered a hamstring injury that saw him missed two matches. It wasn't until on 2 February 2019 when Haroun returned to the starting line–up, in a 2–0 win against Oostende. Despite being sidelined on three more occasions later in the 2018–19 season, he helped the side finished fourth place in the league. Haroun finished the season, making thirty–four appearances and scoring five times in all competitions.