Senderos was expected to leave Arsenal this summer and was lcose to a move to Everton.
The 24-year-old is yet to feature this season for the Gunners following the impressive form of Thomas Vermaelen.
“In this job you have always to be ready and the day you get the chance you can do well,” he told the club’s official website.
“If you are not ready, everybody will say he is not good enough for the level, to play for Arsenal. Now Philippe is back with us, so we will just give him a chance.
“I don’t believe he is starting his career again because we know how good he is, but it is a new start, let’s say.
“He is still very young for a centre-back, he’s 24-years-old and he has the future in front of him. The best 10 years are now coming for him.”