The Greek defender's representative confirms that his client will join the Champions League finalists next season on a five-year deal for an estimated €9.5 million (£8.1m)
The 24-year-old joins BVB on a five-year contract for a transfer fee reported to be in the region of €9.5 million (£8.1m).
"It's done," the player's representative, Kostas Farras, told WAZ.
"It's all signed. My client is now a Dortmund player and looking forward to BVB, coach Jurgen Klopp, the stadium and the fans."
With his future with the Signal Iduna Park side confirmed, the versatile defender will be rooting for his new club as they face Bayern Munich in the Champions League final at Wembley on Saturday evening.