The Belgian has signed for the Spanish giants on a five-year deal, with reports suggesting that Barca have paid £15 million for his services.
The sale may prompt Arsene Wenger to re-enter the market for a new defender.
Vermaelen, however, has not been forgotten quite yet at the Emirates, with his former team-mates wishing their former captain good luck ahead of his move on Twitter.
Podolski, in particular, says he will remember the 28-year-old as a 'top guy,' while Welshman Ramsey says he will remember the pair's regular rounds of golf.
Arsenal legend Ian Wright, meanwhile, even tweeted Vermaelen with the message that it was a 'pity' he couldn't stay and fight for his place in Wenger's side.
Good luck captain in Nou Camp! Will remember you as a top guy and our good time together for Arsenal. AHA!! Thomas all the best for u. Poldi— Lukas-Podolski.com (@Podolski10) August 9, 2014
@T_Vermaelen05 pity you couldn't stay and fight it out.We need quality players like you at the club. Good luck Thomas it's a great move. :-(— Ian Wright (@IanWright0) August 9, 2014