Kevin de Bruyne has completed his move to Chelsea from Genk on a five-and-a-half-year deal.
It is understood that the 20-year-old has joined the former Premier League champions for a fee in the region of £6.7m.
The midfielder announced that he has finalised a switch to Stamford Bridge, but will finish the season in Belgium on loan.
"Yes, it's a little bit of a dream come true," De Bruyne told Chelsea's official website. "I've worked very hard and am still very young but have already played a lot of games. To come to a team like Chelsea is a dream but now it's a reality and I have to work hard to achieve the level that's necessary.
"In the beginning it was a little bit strange to play in such a big stadium but after a while you don't think about it. It is a nice stadium and the atmosphere was very good."
De Bruyne scored 24 goals for the Belgium side in 79 appearances for the club.