The 22-year-old right-back arrives after two seasons on loan at La Liga side Girona, helping them to a surprise third place finish last season.
During his time in Spain, the defender scored two goals and assisted 12 more in 59 La Liga games.
Sebastian Kehl, Dortmund's sporting director described Couto as "a very exciting player".
"His development in Spain was remarkable, and yet he has lots of potential to go even further, which makes him exactly what we wanted for this position."
Since making his debut for Brazil aged 21... Читать дальше...