Early career Buongiorno grew up playing in the
Torino youth sector, with whom he won a
Coppa Italia Primavera in 2017–18. On 14 February 2018, Buongiorno signed a professional contract with Torino, keeping him in the club until 2022. He made his
Serie A debut for Torino in a 4–1 win over
Crotone on 4 April 2018, coming on as a substitute in the 82nd minute, but was forced off due to injury in the 88th minute.
Loans to Carpi and Trapani In the 2018–19 season, he was loaned to
Carpi in
Serie B coached by
Fabrizio Castori. He debuted on 25 September in a 0–1 loss against Perugia as a substitute for
Enrico Pezzi in the 66th minute. Buongiorno returned to Torino the following season, but did not make any appearance. On 11 January 2020, he joined
Serie B club
Trapani for the remainder of the season. He played 13 matches, failing to avoid the relegation for the Sicilian club.
Torino Returning to Turin, Buongiorno renewed his contract with the club until 2024. On 17 December 2020, he made his debut as a starter in Serie A in the 3–1 defeat against
Roma. The following season, with the arrival of
Ivan Jurić on Torino's bench, he began to play more regularly in the club's three-man defence, entering the team's rotations. Buongiorno became a regular starter during the
2022–23 Serie A, and served as club captain on 17 September 2022 in a 1–0 home defeat to
Sassuolo. On 3 May 2023, he scored his first league goal in a 2–0 victory against
Sampdoria in Genoa. At the end of the season, he renewed his contract until 2028.
Napoli On 13 July 2024, Buongiorno was sold to fellow Italian club
Napoli for a reported transfer fee of €35 million plus €5 million in bonuses. With Napoli he signed a five-year contract with minimum release clause of €70 million valid from 2027. ==International career==