Kobel, 22, spent the season on loan from Hoffenheim and joins VfB on a four-year deal.
— VfB Stuttgart (@VfB) July 28, 2020
But in a surprise development, the Swiss youth international pushed for a permanent move to Stuttgart.
Hoffenheim and VfB agreed to not discuss details of the transfer, but Kicker reports the fee to be an initial €4m.
A series of bonuses could push the fee up and Hoffenheim have inserted a sell-on clause.
Kobel made 31 appearances in VfB’s promotion season, keeping 10 clean sheets.