France international defender Axel Disasi has joined Chelsea from Monaco on a six-year contract for 45m euros (£38.57m).
Disasi, 25, offers defensive cover at Stamford Bridge after Wesley Fofana sustained a serious knee injury.
He played in all 38 of Monaco’s Ligue 1 games last season.
“I am really proud to be able to be a part of this great family,” Disasi told Chelsea’s website.
“I hope to achieve very big things here. To win titles. I will do everything I can to achieve those objectives. I am very ambitious.”
The Blues, meanwhile, have agreed a fee with Brighton for goalkeeper Robert Sanchez, while several bids for the Spaniard’s team-mate Moises Caicedo have been rejected by the Seagulls.
Disasi has played four times for France, including featuring as a substitute in the 2022 World Cup final defeat against Argentina, and made 129 appearances for Monaco after joining from Stade de Reims in August 2020.
The centre-back becomes Chelsea’s sixth signing of the summer following the acquisitions of Christopher Nkunku, Nicolas Jackson, Lesley Ugochukwu, Angelo Gabriel and Diego Moreira, as new manager Mauricio Pochettino continues to put his stamp on the squad.
Disasi will compete with fellow central defenders Thiago Silva, Trevoh Chalobah, and Levi Colwill – who signed a new deal on 2 August – for a starting berth, while compatriot Benoit Badiashile will miss the start of the Premier League season with a hamstring injury and Fofana is expected to be sidelined for several months after damaging his anterior cruciate ligament.
“I can’t wait to feel the energy of the fans,” Disasi added.
“The fervour of the fans in the Premier League, the atmosphere, the intensity of the games – it is something that excites me.”