Brighton allowed Percy Tau to join Union Saint Gilloise on a season-long loan deal.
The Belgian are also controlled by Seagulls owner Tony Bloom.
Brighton's development pathway manager David Weir said: "Percy is a talent we have brought to the club for the future, and this loan allows him to play regular senior football here in Europe.
"It is a significant investment for us, and we will be closely watching his progress with Union and monitoring his development over the season."