Capable of playing as a left-back or left-sided forward, Brown racked up 10 goal involvements for Frankfurt last term, including two assists in the Champions League.
The 22-year-old's form caught the eye of Julian Nagelsmann, who selected him for Germany's World Cup squad, and he's also being hunted by Bayern Munich and Arsenal.
A transfer to one of Europe's elite sides is increasingly likely, and although the Gunners courted him as a potential versatile option on the left flank, it appears he wants to stay in Germany.
According to Florian Plettenberg, Bayern have reached a "full verbal agreement" over a summer switch and a long-term contract until 2031 has been agreed.
Brown wants to join the Bundesliga giants with "immediate effect", with Frankfurt sporting director Markus Krösche demanding up to €60 million (£51.8m) for his signature.
Plettenberg does add that a deal could still "fail" if the two clubs don't agree on a transfer fee, but Vincent Kompany is likely to push Bayern hard to finalise a summer move before the World Cup starts next week.
The Champions League semi-finalists are already closing in on a transfer for PSV Eindhoven midfielder Ismael Saibari, and Brown could quickly follow.