The 24-year-old, who was linked with a move to Everton, is determined to force his way back into the Arsenal team.
“For a while the club and myself decided that maybe it was the best to separate, but then in the end the best thing was for me to stay,” Senderos told Arsenal TV Online.
“Playing for Milan was a great experience for me, I have learned a lot and hopefully I can show it when I am on the pitch.
“But I am delighted to be back at Arsenal, it was always my goal to stay at the club and hopefully I can give my best for the team.
“I want to get back into the team and play as many games as possible.”
He added: “I think we have started the season pretty well with a very good win and then the last two (Premier League) games we have lost, but hopefully we can get back into winning again.
“I hope this team comes back and I am sure we have got the quality to do it.”