The Catalan giants had reached an agreement with Los Che at the end of June, and the full-back has finally inked a contract after completing a medicalBarcelona have completed the transfer of Jordi Alba from Valencia for a fee of €14 million.
The Catalans confirmed on their official website on Thursday that the left-back has signed a contract until the summer of 2017.
The Blaugrana had reached an agreement with Los Che over a transfer fee at the end of June, and the Spain international has now signed his contract upon successful completion of a medical.
Jordi Alba, who was unveiled to fans on the Camp Nou pitch earlier on Thursday, spoke of his delight at returning to the club at a press conference.
"I'm very happy to come back home to my family and my people," the left-back, who was released from La Masia in 2005, told reporters. "And thanks to the fans who came to the stadium. I did not expect so many people to come. I'd like to thank all those who made it possible to return home."
Barca vice-president Josep Maria Bartomeu also spoke of his delight at the completion of the transfer, and revealed that director of football Andoni Zubizarreta had been keeping tabs on the 23-year-old for some time.
"We're very excited. We all know about him - he went out to make a career, and is coming home now. We have a long history here," Bartomeu said.
"It was a goal the club had sought for a long time. Zubi told us about his interest in Alba more than a year ago."
The Euro 2012 winner, who has a €90m buy-out clause in his deal, came through the ranks in Catalunya, before being let go and eventually breaking into the first team at Mestalla.