After failing to agree an extension with the Blues, he looks on course to leave as a free agent after ten years on the books.
And Barcelona have wasted no time in arranging a Bosman deal for him to arrive at the Nou Camp in the summer.
According to transfer guru Fabrizio Romano, Christensen decided on a move to the Catalan giants - despite plenty of interest from elsewhere.
Negotiations are still ongoing to finalise the verbal agreement but both parties appear happy.
Christensen is expected to pen a five-year deal until 2027 and will earn around £95,000 per week.
It was reported in Spain on Monday the 54-cap Denmark international would have the second part of his medical yesterday.
The centre-back has made 153 appearances for the Blues, including 26 this season in all competitions.
Barcelona are hoping to spend big on Erling Haaland this summer to play up front next term - while looking for bargains and free transfers to improve the rest of their side amid their financial woes.
Christensen could be joined in Catalonia by Chelsea team-mate Cesar Azpilicueta, who is also being linked with a free transfer to Barca.