Hansi Flick has prioritised bringing in Adeyemi following the free transfer departure of Robert Lewandowski earlier this month with a €22M up front fee already agreed with Borussia Dortmund.
Adeyemi is ready to sign a five-year contract, but the final details of his arrival remain incomplete, as Barcelona await the return of club president Joan Laporta following Spain's 2026 FIFA World Cup title win in the USA.
The club need Laporta to sign off on Adeyemi's arrival with reports from Marca indicating the Germany international is effectively confined to his hotel close to the Estadio Camp Nou.
With the switch not yet fully ratified, Adeyemi cannot train with Flick's squad as part of their preseason return, but he should be registered in time for their summer trip to the UK next month.
The 24-year-old is renowned for his pace and flexibility to play across the attack with double figures scored in each of his last two seasons in Dortmund.