On 4 August 2016, after months of transfer speculation, Zieliński moved from Udinese to Napoli for a reported €16 million.[5] He scored his first goal with Partenopei's shirt on 3 December, in a 3–0 home win against Inter Milan;[6] he ended his first season with six goals. On 31 August 2020, he signed new contract with Napoli until June 2023. On 31 October 2021, not only did he decide the derby between Salernitana and Napoli, scoring the only goal of the game, but with 32 goals he also became the second best Polish goal-scorer in Serie A's history (behind Arkadiusz Milik), beating Zbigniew Boniek's record.[7] On 17 February 2022, he scored a goal for Napoli in a Europa League match against Barcelona which ended in a 1–1 draw.[8] On 7 September 2022, he scored two goals and had one assist in a Champions League match against Liverpool, which concluded in a 4–1 victory for Napoli.[9]
On 4 June 2013, Zieliński made his senior international debut for the Poland national team in a friendly match against Liechtenstein.[10] In May 2018, he was named in Poland's preliminary 35-man squad for the 2018 World Cup in Russia.[11] He provided an assist in the Euro 2024 group stage match against the Netherlands
Personal life
His older brothers Tomasz and Paweł are also footballers.[12] On 15 June 2019, Zieliński married Laura Słowiak[13] with whom he has a son, Maksymilian (born 2021).[14] In 2021, he passed an Italian language exam at the B2 level at the University of Naples in an effort to obtain Italian citizenship.[15] On 6 October 2023, Zieliński formally became an Italian citizen.[16]