Chelsea have officially signed 19-year-old French defender Mamadou Sarr from their sister club, Strasbourg, on an eight-year contract.
The transfer fee is reported to be between €13 million and €20 million (approximately £11 million to £17 million), with some sources indicating a fee of £12 million.
Sarr made 28 appearances for Strasbourg in Ligue 1 last season, playing a key role in their seventh-place finish, which secured qualification for the UEFA Conference League.
He joined Strasbourg in 2024 from Olympique Lyonnais for around €10 million .
Notably, both Chelsea and Strasbourg are owned by the BlueCo consortium, facilitating this transfer.
The signing is Chelsea’s third acquisition of the summer, following the arrivals of midfielder Dario Essugo from Sporting CP and striker Liam Delap from Ipswich Town .
Sarr is expected to participate in Chelsea’s upcoming Club World Cup campaign before potentially being loaned back to Strasbourg, leveraging the multi-club ownership structure for financial and squad flexibility .
Fans and analysts have high expectations for Sarr, with many tipping him to become a world-class central defender within two years .
