On 27 June 2018, Cancelo was signed by Juventus on a five-year contract for €40.4 million, making his domestic league debut on 18 August in a 3–2 away win against Chievo. He won his first trophy with the club in January 2019, featuring the entire 1–0 victory over Milan for the Supercoppa Italiana. He scored his first league goal the same month, as his team came from behind to defeat Lazio 2–1 at the Stadio Olimpico in Rome; he also helped win the decisive match-winning penalty later during the same game, which was subsequently converted by compatriot Cristiano Ronaldo. On 6 October, Cancelo provided an assist for Rodrigo Bentancur in a 2–0 away win over Udinese. On 7 December, Cancelo provided an assist for Mario Mandžukić in a 1–0 home win over against his former club Inter Milan in the Derby d'Italia.