He has stated that during his youth, he struggled with his temper after poor performances from his local team, expressing "I'd be in a foul mood all weekend: atrocious behaviour.

[13] Koundé missed Barcelona's first match of the La Liga season against Rayo Vallecano as the club could not register him as they were over the league's salary cap limit.

[15] Kounde was registered with La Liga on 26 August[16] and made his official debut for the club two days later in a 4–0 win over Real Valladolid at the Camp Nou.

[17] Koundé was a member of France's squad for the group stage of the 2021 UEFA European Under-21 Championship, starting in central defence in all three matches and captaining the team in the 2–0 win against Russia.

[21] Koundé was a member of France's squad for the 2022 FIFA World Cup where he started five of the team's seven matches at right back as they finished as runners-up to Argentina.