The 35-year-old has signed a contract that will take him up till June 2022.
He told the club's official website: "It is a great pleasure to sign for Servette. It is an exciting challenge and I hope I can bring my experience and give my all on the pitch to help this club progress.
"I have already been with the group for some weeks. I am eager to wear the club colours as soon as possible."
Senderos added: "We are very happy with the arrival of Gael at the club. Having been close to him during my playing career, I know all his qualities and his great professionalism.
"He is going to bring his experience of the very highest level to a group in which he is already very well integrated.
"His knowledge of the demands of the very highest level will be beneficial for our youngest players who will benefit from his leadership."
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