The contract is signed until 2031.
Adeyemi joined Dortmund from Salzburg in 2022. Last season, he scored ten goals and provided six assists in 39 appearances in all competitions.
When Adeyemi made his debut for the German national team in 2021, Barcelona coach Hansi Flick was the national team coach, and the duo will now be reunited at club level. For the national team, he has scored one goal in eleven appearances.
The 24-year-old was picked by national team coach Julian Nagelsmann for Germany's World Cup squad.
According to transfer journalist Fabrizio Romano, the transfer is worth a total of 320 million kronor.
