The 23-year-old attacker has played a key role in Freiburg’s success this season, chipping in with nine goals as Christian Streich’s team made a spectacular return to the top flight.
But Philipp will not be around to help the south-western side try to repeat their seventh-placed finish next season, having instead been tempted by the prospect of playing Champions League football at the SIGNAL IDUNA PARK.
The Germany under-21 international has inked a five-year-deal with the Ruhr club. Philipp joined Freiburg from Energie Cottbus in January 2013 and helped the Black Forest club win the Bundesliga 2 title in 2015/2016.
He is Dortmund's fourth major summer signing, joining Mahmoud Dahoud, Ömer Toprak and Dan-Axel Zagadou as the club's new arrivals.
Watch: Check out Philipp's best goal for Freiburg during the 2016/17 season