The Bundesliga club announced the deal via Twitter, saying Dembele has signed a contract until 2021:
ESPN FC's Stephan Uersfeld provided more details about the transfer, suggesting the fee was in the region of €15 million.
Dembele was also linked with a host of other top European clubs—including Barcelona, Bayern Munich, Liverpool, Chelsea, Arsenal, Manchester City and Leicester City, per Ed Aarons of the Guardian—during a breakout season in Ligue 1, but BVB have won the race to sign the exciting youngster.
Get French Football News relayed Dembele's comments on why he opted to join manager Thomas Tuchel's side:
The Frenchman is one of the most talented young attackers in Europe, with no other player of his age as prolific this season, per Opta:
Able to play in a multitude of positions in attack, Dembele will add further strength to a Dortmund forward line that already includes the likes of Marco Reus, Henrikh Mkhitaryan, Pierre-Emerick Aubameyang and Shinji Kagawa.
Dortmund will undoubtedly be delighted to have beaten off intense competition for Dembele's signature and have done well to confirm his signing before the opening of the summer transfer window, per European football writer James Horncastle:
As ESPN FC's John Brewin noted, though, it may not be long before rivals Bayern come knocking for the France under-21 international, having poached Mario Gotze, Robert Lewandowski and Mats Hummels from Dortmund in recent years:
For now, however, BVB have bagged themselves an excellent player who will only improve as he gains more experience. He will undoubtedly be a great help to them in the UEFA Champions League and in their attempts to wrest the Bundesliga title back off Bayern next season.