The club confirmed the transfer in a statement to SID (h/t Goal's Ronan Murphy):
Per Bild (in German), Dortmund will activate the €25 million release clause in Brandt's contract, and the transfer should be completed at some point this week. He'll be paid €8 million per year. Brandt told his team-mates the news on their way to a vacation in Barcelona on Monday night.
Last week, sporting director Rudi Voller told Sky Sports News HD (h/t Goal's Dane Sheridan) Brandt's future would be decided this week: "We know exactly which clubs have knocked [for Brandt]. Brandt has some requests, and in the next five, six or seven days there will be a decision. By reaching the Champions League, we hope we have a small or big chance (that he will stay)."
Per sports writer Manuel Veth, Brandt previously hinted he could stay at the club if it secured UEFA Champions League football for next season:
Leverkusen did just that, finishing the season in fourth place behind Bayern Munich, Borussia Dortmund and RB Leipzig, but the midfielder still decided to leave. According to Goal's Chris Burton, he was also linked with Liverpool and Juventus.
The 23-year-old made his Bundesliga debut in 2014 and has been among Germany's top talents ever since. He's a full German international as well as one of the Bundesliga's best creators:
Brandt stands out for his versatility and well-rounded skill set. While he's mostly known as an attacking midfielder, he can also slide further back and play closer to his own defence or split out wide and play as a winger.
He scored seven goals and added 11 assists in the Bundesliga this season, netting in his final appearance, a 5-1 win over Hertha.
Here is a profile of the rising star:
Losing Brandt for just €25 million is a serious blow for Leverkusen, especially as he'll join one of their Bundesliga rivals. Dortmund seem determined to strengthen their squad with domestic stars this summer, with Borussia Monchengladbach's Thorgan Hazard also close to joining, per Sport1 (h/t Burton).