The center back has been linked with Manchester United, but Jurgen Klopp has issued a statement of intent by handing the defender the armband ahead of the new season.
The 25-year-old defender wasn't involved as BVB fell to a shock 4-0 friendly defeat to Liverpool at Anfield on Sunday, just three days before facing Bayern Munich in the German Supercup.
Dortmund attempted to lift some of the post-match gloom by announcing the news of Hummels' appointment via its official Twitter account after the match.
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"Mats Hummels will be the new captain of Borussia Dortmund. Marco Reus and Roman Weidenfeller will be the alternatives."
Sebastian Kehl had previously been BVB's leader, but his advancing years and reduced playing time saw the midfielder step down from the role.
In a recent statement he said: "This important task has filled me with fun and pride. It makes sense now to pass the baton. For I have now the opportunity to be my successor with advice and practical help and support with the experience gained. I like to have completed this task, but now the time is right."