Bellerin returned to Barcelona on a free transfer on transfer deadline day, signing a one-year contract with the Camp Nou outfit.
Arsenal poached Bellerin from the Barcelona academy back in 2011 and the Spain international went on to play 239 games for the Gunners, winning three FA Cups.
Bellerin spent last season in Spain with Real Betis, helping Manuel Pellegrini's side win the Copa del Rey.
The 27-year-old will now get the chance to feature for Barcelona's senior side following his move to Xavi Hernandez's side.
Bellerin has however expressed gratitude to the Arsenal fraternity after his exit was sealed.
"Hello Gunners. Feels like it was only a couple of years ago when I touched down in London for the very first time," Bellerin wrote on social media.
"From day one I truly felt at home and I've said time and time again how this city has shaped me into who I am, and how much I owe it. It's with a lot of sadness that today I say goodbye to this club, the fans, the staff, the players and our family all together.
"There's been highs, so high, and lows, so low, but I've enjoyed thoroughly every single experience I've lived with you Gunners. It's not always been easy being an Arsenal player these past 11 years, but it's always been an honour to carry the weight of this badge and defend it almost 250 times in front of you all.
"I want to thank Arsene, Francis, the late Steve Rowley, Steve Bould, Neil Banfield, Unai Emery, Freddie Ljungberg and Mikel. Thank you to the staff who work tirelessly for us to have it all ready when we step onto the pitch.
"Physios, conditioning coaches, doctors, chefs, kit men, cleaners, security, and everyone else who is a part of this family. Thank you to the players who have made my time here unforgettable.
"And most importantly, thank you Gunners, thank you for your continued support throughout all these years, for how supportive you were in the good and the bad, for how enjoyable it's been to play in this beautiful stadium and for sharing together every single step of this journey of mine.
"With the sadness of a good bye, but the excitement of a new beginning, I say to you all 'thank you'. Once a Gunner, always a Gunner."
