The 20-year-old midfielder has put pen to paper on a five-year contract at Stamford Bridge.
The Dutch international told the club's official website: "I'm very happy to be here at such a nice club with great players. I am really happy, the stadium is good and the training ground is fantastic.
"I know about all the players and will meet them on Monday. I expect a lot, I've watched matches and it's really nice to be here."
Van Ginkel has won one international cap for the Netherlands.