On 6 January 2018 during their 2017–18 season, Arzani was brought on as a substitute with the senior side and provided two assists in a 2–1 comeback win against Wellington Phoenix FC. He provided two more assists in his first senior start on 9 January against Perth Glory FC. Arzani scored his first A-League goal on 25 January 2018 against Newcastle Jets FC. After just four starts from his club's 18 league games, Arzani led his team for the most successful dribbles with 31. He won the A-League player of the month award for his performances in January. By April 2018, Arzani led the league in successful dribbles with 89, provided the most assists out of all under-23 players in the league, and was nominated for the A-League Young Footballer of the Year award. At the conclusion of the season, it was announced that he won the award. He was subsequently named in the A-League Team of the Season. In July 2018, Arzani won the Harry Kewell Medal for the best Australian male under-23 player.