Chelsea have signed Mamadou Sarr from Ligue 1 side Strasbourg, the club have confirmed.
The 19-year-old has signed an eight-year deal that runs until 2033.
Centre-back Sarr came through the youth system at Lens before moving to Strasbourg in 2024.
He made 29 appearances for the club in all competitions this season as they qualified for next season's UEFA Conference League.
"His talent has been recognised by his country as he has been capped at various youth levels, with his latest appearances coming for France's under-20 side," Chelsea said in a statement.
"Welcome to Chelsea, Mamadou!"
Sarr has also played for France at U17, U18 and U19 level.
The move comes with striker Liam Delap having also made the move to Stamford Bridge this summer, while winger Jadon Sancho has confirmed he will go back to Manchester United, with his loan deal coming to an end.
