Chinaglia rose to fame as a prolific goalscorer in Italy's Serie A, playing for S.S. Lazio, scoring 12 goals in his debut Serie A season, including a notable goal against European Cup holders Milan, led by Gianni Rivera. He scored 9 goals in his second season, which was insufficient to prevent Lazio from being relegated to Serie B the following season. Despite Lazio's poor league form that year, Chinaglia won the Coppa delle Alpi with Lazio in 1971, defeating Basel 3–1 in the final. He helped Lazio to gain promotion to Serie A during the following season, leading the club to a second-place finish in Serie B that year, and finishing the season as the leading goalscorer in Serie B, with 21 goals. The following season, Chinaglia scored 10 goals in Serie A, as Lazio narrowly missed out on the title, losing it to Juventus on the final matchday. During the 1973–74 season, he led the top Italian league in scoring, with 24 goals, and he helped his team to the Serie A title that year, scoring the decisive goal from a penalty in a 1–0 win over Foggia. He was named the club's captain during his final season in Italy, concluding his European career with 14 goals. In total, he scored 98 league goals for Lazio in 209 appearances, 77 of which were scored in Serie A, in 175 appearances. He scored 122 goals in 246 appearances in all competitions for Lazio, scoring 13 goals in 28 Coppa Italia appearances, and 9 goals in 11 European matches.