Germany Under-21 defender Thilo Kehrer completed his move to Paris Saint-Germain on Thursday by signing a five-year contract, the French champions announced.
"I could not imagine a better club to push my development and achieve my goals," Kehrer was quoted as saying on the PSG website.
The rising German star is PSG's second signing of the summer after veteran Italian goalkeeper Gianluigi Buffon.
"Several big clubs were chasing his (Kehrer's) signature, and he chose Paris Saint-Germain to continue his climb through the ranks of European football," said PSG chairman and CEO Nasser Al-Khelaif.
"This transfer is in keeping with our policy of producing, and attracting, the talented stars of tomorrow, with the aim of helping them improve alongside great and experienced players."
Schalke announced on Sunday that they had agreed to sell the 21-year-old to PSG for a reported fee of 37 million euros ($42.3 million).
"The economic dimension of this transfer and the desire of Thilo to accept the PSG offer moved us to support this transfer," said Schalke's director of sport Christian Heidel.
Kehrer, who has yet to make his senior Germany debut, was part of the German team which won the Under-21 European championships last month and played 27 Bundesliga matches last year for Schalke.
"From the ball boy from the 'Knappenschmiede' (Schalke academy) to the first-team squad, the German Youth team championship and my first home derby win (against Borussia Dortmund)," Kehrer wrote on Instagram.
"During my time at Schalke, I not only learned a lot, I'm met great people who shaped me and made me the person and player I am today.
"I'm so grateful for that."