While the 18-year-old has already secured his long term future with the Gunners, he will head back to his old club for one more year before moving to London.
Saliba believes that at his age, it is the right move to ensure that he develops correctly and with the right amount of pressure.
He said to reporters about staying at Saint-Etienne for another year: "Well, it was important first of all because I wanted to prove myself for another year at Saint-Etienne, before I come to try and establish myself here at Arsenal.
"This is a big club, and when you come here, you need to be ready.
"I'm going to try and have a great season with the club that developed me in order to be ready for Arsenal."