Youssouf Fofana was born on 10 January 1999 in Paris and came through Parisian youth football before joining Strasbourg's academy in 2017. He made his Ligue 1 debut for Strasbourg in August 2018 and helped the club win the Coupe de la Ligue in 2019.
In January 2020 he joined Monaco for around €15 million, becoming a regular starter in the principality club's midfield over four seasons and accumulating 143 Ligue 1 appearances. In August 2024 AC Milan signed him on a four-year contract, and he was part of the Rossoneri squad that won the Supercoppa Italiana in his first season at the club.
He earned his senior France debut in September 2022 and featured prominently at the 2022 World Cup, appearing in six of France's seven matches and coming on as a substitute in the final defeat to Argentina. He scored his first international goal against Gibraltar during Euro 2024 qualifying and went on to feature in the Euro 2024 finals.
A 1.85 m central defensive midfielder, Fofana is built around physical strength, stamina, ball-winning and aggressive pressing, and is used by Milan as a structural anchor who lets more creative midfielders such as Modrić, Reijnders or Loftus-Cheek operate higher up the pitch.