The coveted 22-year-old attacker has chosen to move back to his hometown club, his current and future sides have confirmed. He has signed a five-year deal which will begin in July
The Germany international has been heavily linked with the Bundesliga title holders, as well as Bayern Munich, but the official Gladbach website has confirmed that he has opted to join Jurgen Klopp's side, having agreed to a contract until 2017.
"To me it is important to clarify that this is not a decision against Gladbach. I have had a wonderful time here," Reus said. "Borussia have given me the chance to prove myself in the Bundesliga and to develop into the player I am today.
"But I've decided that in the coming season I'll take the next step and play for a club that contends for the championship and gives me the guarantee to play in the Champions League. This is an opportunity I see in Dortmund."
Reus' future employers are delighted with the attacker's acquisiton.
"In Marco Reus we sign our absolute preference for an offensive player," Dortmund sporting director Michael Zorc told his club's official website. "We are delighted that Marco has chosen BVB, despite top class competition."
Bayern clarified their interest in Reus earlier this season, but the league champions were able to secure his services for a reported €17.5 million, the value of his buy-out clause.
Meanwhile, Monchengladbach have also confirmed that midfielder Roman Neustadter will leave the club when his contract expires at the end of the season to link up with either Schalke or Bayer Leverkusen.