Thomas Vermaelen has completed his move to Barcelona after signing a five-year deal on Sunday.
The 28-year-old defender, who has played 150 times for Arsenal in five seasons, has switched the Emirates Stadium for the Nou Camp after putting pen to paper on the contract that will see him join the Primera Division club.
Barcelona said in a statement on their website: "Thomas Vermaelen is now officially an FC Barcelona player.
"A few minutes past 11:15am, the player signed a contract with the Catalan club. It is an agreement that binds him with the club for the next five seasons, until 2018/19."
Barcelona agreed a deal with Arsenal to sign the player on Saturday, with both clubs announcing the news.
Arsenal confirmed Vermaelen passed his medical in Barcelona earlier that day.
The fee is undisclosed for a player who had been club captain for the Barclays Premier League side for the past two seasons but was frequently on the bench last term, with Per Mertesacker and Laurent Koscielny the first-choice pairing at centre-back.
He made only 13 starts in all competitions and 21 appearances in total for Arsenal during the campaign, which concluded with him being an unused substitute in the Gunners' FA Cup final victory over Hull as they collected their first trophy in nine years.
Vermaelen was initially an integral part of the London club's defence after signing from Ajax in 2009, but form and fitness have subsequently put his starting spot in jeopardy.
Vermaelen had been linked with Manchester United, but it is understood that Arsenal proposed a swap deal which the Red Devils were not prepared to do.
While indicating on Thursday that United were among the clubs to have made an offer for Vermaelen, Arsenal boss Arsene Wenger also said he would prefer any sale to be made to an overseas side.