Fabrizio Romano, a transfer market expert, revealed, through his account on Twitter, that Alonso signed Barca in a free transfer deal, after the termination of his contract with the Blues.
He explained that the Catalan team will announce the deal officially on Friday morning.
Barca finally got his wish after lengthy negotiations with the London team, which moved in the past hours to include Pierre Emeric Aubameyang from the Blaugrana.
It is noteworthy that Barcelona announced a short time ago, that it had reached an agreement with Hector Bellerin, to sign him for free after the termination of his contract with Arsenal.