David Luiz has returned to Chelsea after leaving the Blues in 2014 for PSG in a record defender deal.
The Brazil international rejoins the club on a three-year contract, and for a transfer fee believed to be around £32m.
“I’m delighted to return to Chelsea. We had a fantastic story during my first time at the club and I want to help the team and Antonio Conte achieve a lot of success,” he told the club’s website.
“I always had a wonderful relationship with the fans and I am looking forward to wearing the blue shirt at Stamford Bridge once again.”
The 29-year old won the Champions League, Europa League and the FA Cup with the Premier League club in his last stint.