Boniek transferred to Italian football giants Juventus in 1982. With Juventus he won the Coppa Italia in his first season, also managing a second-place finish in the league and reaching the 1983 European Cup Final in the same season. The following season, his performances proved decisive, as Juventus won both the Serie A title and the Cup Winners' Cup in 1984, with Boniek scoring the matching-winning goal in the 2–1 victory over Porto in the final of the latter tournament in Basel; he followed up these victories by claiming the European Super Cup later that year, scoring twice in the 2–0 win against Liverpool. He also won the European Cup in 1985, against Liverpool once again, winning the penalty that Michel Platini subsequently converted to win the title for Juventus, although the team's victory was overshadowed by the Heysel Disaster.