The 25-year-old defender, who joined Barcelona at the age of 11, has inked a four-year contract to stay with the "BVB" until June 2020, both clubs confirmed on Saturday, reports Xinhua.
Bartra made his debut for Barcelona in February 2010 to make 58 league appearances plus 22 outings in the UEAF Champions League.
(Winning third straight Euro will be difficult for Spain: Pedro Rodriguez)
Despite his young age he already collected a number of titles. He won the Champions League title and Spanish Cup twice as well as the Spanish championship five times. He also earned six international caps for Spain's national team.
Dortmund's new arrival is said to replace former defender and captain Mats Hummels, who returned to his youth club Bayern Munich this summer.
Bartra's new club completed the Bundesliga season 2015/2016 on the second place of the standings.