The 32-year-old, who moved to Stamford Bridge from Marseille in 2012, has less than seven months remaining on his current contract and is at risk of leaving the Blues for free in June 2022.
According to El Nacional, talks between Azpilicueta's representatives and Barca are at an advanced stage ahead of potentially agreeing a pre-contract agreement in January.
Any potential transfer for Azpilicueta to Camp Nou could, however, end Dani Alves's brief return with Barcelona.
The 38-year-old Brazilian, who re-signed for the club last month, is not able to play until January, but Azpilicueta's arrival could prevent Alves from extending his short-term contract beyond the summer with Barca due to financial reasons.
Azpilicueta has made 444 appearances for Chelsea across all competitions, winning a total of eight trophies including two Premier League titles, two Europa Leagues as well as last season's Champions League. body check tags ::