Hummels extends Dortmund contract
22-year-old Hummels, who joined Dortmund from defending champions Bayern Munich, won the last of his three caps in last month's 1-1 draw with Italy and is tipped as a future star of the national side.
"We have, in Mats, a very successful footballer who plays a significant role in our long-term planning and we have taken into account his sporting development," said the club's director of sport Michael Zorc.
Hummels' signature means Dortmund will keep the core of their team which currently enjoys a nine-point lead at the top of the Bundesliga table.
Coach Jurgen Klopp has also been signed up until 2014. Borussia host fifth-placed Mainz in the Bundesliga on Saturday night.