On 12 August 2018, Vidal made his debut for the club after coming on as a substitute in a 2–1 victory over Sevilla FC as his side won the 2018 Spanish Super Cup. On 28 October, Vidal came on as a substitute in the 84th minute of "El Clásico". 3 minutes later, Vidal scored his first ever goal for Barcelona to cap off a 5–1 home win over rivals Real Madrid in La Liga. On 27 April 2019, he assisted the winning goal by Lionel Messi in a 1–0 win against Levante, to secure the La Liga title.