The Belgium international passed a thorough medical earlier on Saturday and has now completed a move to the Catalan club.
The center back agreed to join the Spanish side late last week, after rejecting the overtures of Manchester United in favor of a summer switch to Camp Nou and flew in to Barcelona on Saturday morning for his medical ahead of the transfer.
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The 28-year-old has been blighted by injuries over the last few seasons and was given a thorough, two-part examination by the Blaugrana at the Hospital de Barcelona and later at the Clinica de la Creu Blanca.
However, Vermaelen came through the tests without any problems and is set to become the second center back to join the club this summer, after Jeremy Mathieu arrived from Valencia last month.
The defender, who becomes the third former Arsenal captain to join Barca in seven years (after Thierry Henry in 2007 and Cesc Fabregas in 2011), could be unveiled at Camp Nou on Sunday.