The Gunners terminated his contract on mutual consent, allowing him to leave for free in January.
Mustafi signed a 6-month contract with Schalke to replace Ozan Kabak who headed off to Liverpool.
“Hi Gunners,” wrote Mustafi. “After four years, 151 matches and two FA Cup trophies, I just wanted to say thank you to the Arsenal community, our great staff, the fans and of course my team-mates.
“Together we went to through good and not so good times, but we stood together. Arsenal is a fantastic club with a great tradition and I always felt, that it is a pleasure and honour to wear the AFC jersey.
“My family and I will always remember the time we had in London and with Arsenal! Gooners, I wish you all the best! Thank you! Musti.”
Shkodran Mustafi leaves after four-and-a-half years of association with the club. Some fans expected the German to leave sooner but he player his way back into Mikel Arteta’s starting line up last season.
Mustafi had some memorable contributions to last season’s Europa League and FA Cup campaigns, eventually missing the final due to injury. But overall, his £35m signing from Valencia was a bad bit of business that the club has, fortunately, put past them this January.
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