The Bundesliga outfit took advantage of a similar clause to sign the 24-year-old from Borussia Monchengladbach last summer, and he went on to play a major role in their path to the Champions League final.
Reus has continued to shine in Jurgen Klopp's side this season, with his performances reportedly attracting attention from Arsenal, Manchester United and Paris Saint-Germain.
Any sides considering an offer for German international will be encouraged by Hans-Joachim Watzke's revelation, with the Dortmund executive confirming the existence of the clause.
"Marco Reus possesses a release clause option in his current contract at our club," Watzke told SPORT1media. "He could leave our club due to that.
"He is, however, the only player in our first-team squad that has such a contract clause."
Dortmund are said to be preparing a new deal for Reus that would increase his salary but remove the release clause in his contract, which is currently due to expire in 2017.