Belgian defender had been having a medical with the Spanish club on Saturday.
The Belgian defender arrived in Barcelona on Saturday to complete his medical and personal negotiations with the club, and the Catalans have now confirmed his signing.
Vermaelen made 150 appearances for the Gunners since joining from Ajax in 2009, but was reduced to the substitute’s bench for the majority of last season. Defenders Per Mertesacker and Laurent Koscielny have become regular centre-half choices, and have left Vermaelen needing to leave the club for first-team football.
Manchester United were thought to be another team chasing the 28-year-old’s signature, after the departure of Rio Ferdinand and Nemanja Vidic has left them short at the back. But it was Barcelona who acted quickest, eager to fill the void left by the retired Carlos Puyol.
Despite holding the captaincy at both Ajax and Arsenal, Vermaelen has arrived a little too late to have a say in the role at the Nou Camp. Barca confirmed just the other day that the armband would be shared four-ways between Xavi, Andres Iniesta, Lionel Messi and Sergio Busquets.
Vermaelen is likely to partner former Manchester United defender Gerard Pique for the new season, and will hope to firm up a defence that conceded too many goals last season. The Spanish giants failed to win a trophy for the first time in recent memory last time out, and have appointed former player Luis Enrique to stop the rot.
Arsenal fans will be glad that Vermaelen does not add to a long list of players who have left the club for other Premier League opposition, as he prepares for his new chapter in Barcelona.