Sebastian Rudy will spend the 2019-20 season on loan at Hoffenheim, which has re-signed him from Schalke.
Rudy enjoyed seven seasons with Hoffenheim before joining Bayern Munich in 2017.
He is heading back to the Rhein-Neckar-Arena after the season-long loan deal was announced on Wednesday.
"Last season did not go optimally for me, which makes me all the more motivated to return to my former strength here at my former club," Rudy told Hoffenheim's official website.
"To that end, the conditions here at Hoffenheim are almost perfect – I know the people and conditions at the club, and I know that me and my way of playing football are valued here.
"I'm looking forward to working together with Alfred [Schreuder] and his coaching staff, and so far I've only heard good things from my former colleagues."
Rudy signed a four-year deal to wrap up a transfer to Schalke from Bayern Munich worth a reported €16million in August 2018.
But the midfielder started only 17 Bundesliga games for the club and has been given the green light to depart on loan.
"Sebastian Rudy has certainly not had an easy year at Schalke," said the club's sporting director Jochen Schneider. "Unfortunately, the 2018-19 season didn't go the way that Sebastian wanted, the way the team nor the rest of us were hoping for.
"When he came to us and told us of his wish to be loaned out to his former club, Hoffenheim, for 11 months, we complied. We wholeheartedly wish Sebastian a successful season in his old home."
Rudy has played 27 matches for Germany, but the 29-year-old is yet to feature for his country since making a single appearance during its poor performance at the 2018 World Cup.