The 26-year-old announced last month that he will not be extending his stay at the Allianz Arena after five years at the club.
Borussia Dortmund have now confirmed that Sule’s next destination will be the Signal Iduna Park as he has agreed terms on a four-year contract as a free agent.
The Germany international joined the Bavarians for €22m from Hoffenheim in the summer of 2017 and has made 159 appearances in his time at the club.
Sule has won four Bundesliga titles, one UEFA Champions League, three DFB-Pokals among numerous other honours at Bayern.
"We're delighted that we have managed to sign Niklas Sule, a Germany international, on a free transfer and have tied the player down for four years," said Dortmund sporting director Michael Zorc.
Sebastian Kehl, who will succeed Zorc later this year, added: "Niklas has shown during the course of personal talks that he is really keen on Borussia Dortmund.
"He possesses a lot of experience, composure in his build-up play and the necessary physicality to take the next step with us from this summer onwards."
