Late on Friday evening, the Spanish giants confirmed that Dortmund had activated Bartra's €8m release clause.
BVB then added that the 25-year-old has signed a four-year deal at the Signal Iduna Park, seeing him through until 2020.
A steal of a deal
Bartra - who already has two UEFA Champions League titles, two Copa del Rey crowns and five La Liga winner medals to his name - could be Dortmund's perfect centre-half.
He is made in the mould of Hummels; comfortable on the ball, tall and good on the ground. The Spaniard may not be at the same level just yet, however.
That could be where Thomas Tuchel comes in, though. The BVB boss has already settled Julian Weigl into the top level of German football, so this may be more of the same.
A chance to establish himself?
Despite being a regular in the cup competitions, only once has Bartra featured in more than half of a La Liga season.
His appearance tally stands at 103 after making his debut in February 2010; his potential seemingly hasn't been let flourish at the Catalan outfit.
Barca wish Bartra well
As they announced the news, Barcelona commented: "FC Barcelona wish Marc Bartra all the best in his new phase of his career as a player."
They added, "He will be invited to say goodbye to the fans personally at the start of next season." A nice touch from his now former club.
Should all of the final details of the move be ironed out, Bartra will make his competitive debut against Bayern Munich in the DFL-Supercup.