The 26-year-old Denmark international has not agreed an extension to his expiring contract and is expected to sign for Barcelona on a free transfer.
Christensen was one of Chelsea's longest serving players, having joined the club's academy as a teenager in 2012 before making his first team debut in 2014.
He had to bide his time before becoming a regular at Stamford Bridge, spending two years on loan in the Bundesliga with Borussia Monchengladbach between 2015 and 2017.
Christensen would go on to make 161 appearances in total for the Blues, winning a host of laurels.
Chelsea said on their official website: “Christensen’s Chelsea contract expires this summer, bringing to an end his 10 years as a Blue, during which he graduated from our academy and subsequently secured a regular place in our senior squad, playing 161 games.
“He would experience success in the FA Cup, Europa League, UEFA Super Cup, FIFA Club World Cup and, most memorably, the Champions League. He came off the bench in the first half of the final in Porto last year and was crucial to our defensive efforts as we overcame Manchester City.”
Also departing Chelsea are Danny Drinkwater, Charly Musonda and Jake Clarke-Salter.
Antonio Rudiger has already signed for Real Madrid.
