Sunderland manager David Moyes has made Chelsea defender Papy Djilobodji his first signing in an £8million transfer.
The Senegal international, who can also play as a defensive midfielder, has signed a four-year contract at the Stadium of Light.
The 27-year-old spent the second half of last season on loan at Werder Bremen, helping them to Bundesliga safety with an 88th-minute winner against Eintracht Frankfurt on the final day of the campaign.
Djilobodji began his career in Senegal with ASC Saloum before joining French club US Senart-Moissy in October 2009.
He joined Nantes in 2010 and went on to make 171 appearances, scoring nine goals across five years.
Djilobodji joined Chelsea last summer for a reported £2.7m, but his only appearance came as an 89th-minute substitute in a 4-1 Capital One Cup win at Walsall.
However, despite his minimal impact at Stamford Bridge, Chelsea have trebled their money on a player who has been capped 12 times by Senegal and appeared at the 2015 African Cup of Nations.
“Chelsea Football Club thanks Papy for his service and wishes him well for the future,” said a statement on the London club’s official website.
Djilobodji told http://www.safc.com: “I’m so happy to join Sunderland, I believe we are going to do something this year.
“Sunderland Football Club is a big club, a big team, with big fans.
“We are going to do our best to give the fans what they deserve.
“The coach (Moyes) called me yesterday and I was so happy, we are going to work to improve.”