The 25-year old Serbian midfielder has signed a five-and-a-half-year deal with the Blues, joining from Benfica, where he arrived after initially exiting Stamford Bridge three years ago.
Matic has joined Chelsea for a reported £20.7million and admitted he was over the moon to be returning.
"I am very happy for this opportunity to be back at this club," he told chelseafc.com.
"I feel very good because of that and just want to say I will give my best to help the team and make the Chelsea fans happy."
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