The 20-year-old has signed a four-and-a-half-year contract with the Premier League giants.
“I am very happy to sign for Chelsea, a world famous club with a reputation for major success,” he told the club website.
“I am delighted to be in the Premier League, the best league in the world, and can’t wait to meet my team-mates and get going.
“I am still at the beginning of my career but I believe this is the place to develop and learn from some of the best players in the world.”