The Egypt international spent three years at the Swiss club.
“I didn't have a lot of experience before I moved to Basel," Elneny told Arsenal Player. “I learned a lot and gained plenty of experience playing for them in both the Champions League and Europa League.
“I was there for three years and also learned how to be more punctual both on and off the pitch, and not to fear any opponent we face. I liked the club and enjoyed my time there.
“I have good memories of my time playing for them. It will be a good opportunity to see everyone again and the fans, who I have a very good relationship with."