The 28-year-old left the Bernabeu in a £42.5m switch to North London in 2013, and after a stuttered start to life at Arsenal, the playmaker has become an influential figure in Arsene Wenger's team.
The club have opened negotiations over a new contract for Ozil, but a deal is yet to be agreed, which has sparked reports that a Madrid reunion could be on the cards.
The German World Cup winner was asked during an interview with Marca if he would be open to playing for the Spanish giants again, to which Ozil replied: "You never know.
"I am very happy playing in such a big club like Arsenal, which has amazing fans and they also encourage me a lot. I am playing very well in London, but in football you never know. We'll see what happens in the future."
Ozil, who has made 134 appearances for the Gunners since 2013, has scored seven goals in all competitions this season and registered three assists.
In Madrid the midfielder won three major trophies, including the La Liga title, during a three-year spell.