Dortmund's squad returned to training for the 2026-27 season on 12 July, but Adeyemi was a notable absentee from the group at their performance and diagnostic testing headquarters in Brackel.
Rumours have been swirling about his future in the Bundesliga with several top European clubs reportedly chasing his signature.
The most notable of which was LaLiga giants Barcelona, who are believed to have submitted a bid in the region of 30 million euros last week.
It now appears as if their were some credibility to the rumours after Dortmund revealed Adeyemi was allowed to miss the first day of training in order to hold discussions with another club over a potential transfer.
Reports indicate the full transfer package will include 22 million euros upfront, with another 8 million euros in add-ons, as well as a clause that will entitle Dortmund to a percentage of any profit Barcelona may make on a future transfer.
Adeyemi has made 98 Bundesliga appearances for Dortmund after joining the club from RB Salzburg in 2022 and has scored 23 goals.
He was a surprise exclusion from Germany's 2026 FIFA World Cup squad after being a prominent member of the side during qualifying.
Barcelona head coach Hansi Flick is a keen admirer of Adeyemi and is very familiar with his style of play after having given the forward his debut for Germany when he was in charge of the national team.
Once completed, Adeyemi will become Barcelona's second signing of the off-season after bringing in English winger Anthony Gordon in a blockbuster 70-million-euro deal from Premier League side Newcastle, with the club also still interested in signing another striker to replace Robert Lewandowski.
Barcelona president Joan Laporta has welcomed the club's move for Karim Adeyemi, saying everyone at the club is excited about bringing the Germany international winger to Camp Nou.
Winger Ryunosuke Sato is set to become the first Japanese player to play for Valencia after he signed a five-year deal with the LaLiga club.
FC Barcelona have reportedly reached an agreement with Borussia Dortmund to sign Karim Adeyemi, with the Germany international now closing in on a move to the Spanish champions.
Barcelona are approaching a pivotal stage in determining Ferran Torres' future, with the Spain international attracting interest from Paris Saint-Germain while his contract situation is unclear.
