Albion’s under-18s boss is leaving to take over at IF Elfsborg in his native Sweden.
Assistant coaches Steve Menzies and Tomer Hemed will take charge of the under-18s on an interim basis, starting with next Tuesday’s FA Youth Cup tie against Sunderland.
Hamberg was part of Graham Potter’s coaching staff with the Seagulls and returned in charge of the under-18s ahead of this season.
He has also worked with the Swedish national squad this term but has always made it clear he saw himself as a head coach.
Albion sporting director Jason Ayto said: “Bjorn has been a well-respected and popular coach here and, while we are sorry to see him leave his role with our under-18s at this time, we fully support his desire to step into senior management. We wish him and his family all the very best for the future.”
Elfsborg have completed their pre-season friendlies are about to tackle three cup games before the league campaign gets under way in early April.
They finished eighth in the table last term and face Gothenburg in their opening Allsvenskan game on April 6.