The 24-year-old joins the 2012/13 UEFA Champions League finalists from French side AS Saint-Etienne, for whom he scored 19 goals and set up another 14 last season.
"We're pleased to have got our man in Pierre-Emerick Aubameyang," beamed BVB sporting director Michael Zorc. "He's extremely versatile in the forward positions, has exceptional speed and is a real goal-threat."
The 30-time Gabon international's performances in Ligue 1 are certainly testament to that, the former AC Milan star having rounded off the 2012/13 campaign as the French top flight's second-highest scorer.
The Laval native will link up with his new team-mates once they have returned from their Austrian training camp in Tirol (July 3-6).