The highly-rated teenage midfielder will continue his development with Lucien Favre’s side at Westfalenstadion next season
Goal has learned that an agreement has been reached between the two clubs which will see the 18-year-old spend the 2020-21 campaign at Westfalenstadion.
Dortmund will have the option to extend the loan by an extra year, but no purchase clause has been included in the final deal.
BVB boss Lucien Favre confirmed that Reinier’s arrival was imminent after watching his side beat Austria Wien in a pre-season friendly on Sunday.
“We want to loan him. It’s in the pipeline. From what I’ve seen, he’s very good offensively and a very, very good finisher,” said Favre.
Madrid forked out €35 million (£30m/$39m) to bring the midfielder to Santiago Bernabeu from Flamengo in January.
He committed his future to the Spanish champions through to 2026, but La Liga‘s registration rules prevented him from joining up with Zinedine Zidane’s first team.
Reinier has had to make do with a role in Madrid’s Castilla set-up due to the fact only three non-EU players are allowed in the senior squad, with Vinicius, Rodrygo and Eder Militao currently filling those spots.
Madrid are hoping that the talented teenager can get plenty of minutes under his belt at Dortmund, who have carved out a sterling reputation for their development of younger players in recent years.
The likes of Jadon Sancho, Erling Haaland, Giovanni Reyna and Jude Bellingham have all been given a platform to further their careers by the Bundesliga giants, and ex-Madrid loanee Achraf Hakimi was one of their top performers last term.
Bellingham became Dortmund’s second signing of the summer when he joined the club from Birmingham City in July, with former Paris Saint-Germain full-back Thomas Meunier arriving on a free transfer earlier in the month.
Dortmund sporting director Michael Zorc has publicly stated that the 20-year-old will stay put for at least another season, but the Red Devils are still optimistic of finalising a transfer before the window closes.