Dani Alves, who invested eight years at the Nou Camp with Xavi, will team up with his new team-mates after the international break but will be unable to play until January.
The defender will bring an abundance of experience to Xavi’s young squad, having triumph a record 46 trophies in his career.
The 38-year-old has not had a squad since he left Sao Paulo in September after a controversy over due wages.
A club statement read: “FC Barcelona and Dani Alves have reached an agreement in principle for the player to join the football first team for the remainder of the current season.
“The Brazilian will be joining training from next week but will not be able to play until January.
“The club will announce the full details at his official presentation as a new FC Barcelona player.”