The 21-year-old Bafana Bafana attacker has signed a four-year contract with the Belgian club after successfully completing his medical and agreeing to personal terms. The deal will keep him at Union Saint-Gilloise until 2030.
Speaking after his unveiling, Mofokeng expressed his excitement at taking the next step in his career and is eager to make an immediate impact as the club prepares for its UEFA Champions League qualifying campaign.
"I'm very happy to be here," Mofokeng told the club's official website.
"It's a dream to play in Europe and to begin our Champions League qualifying campaign soon. The past year has been very special, with the league title, my first FIFA World Cup with South Africa and now this important step in my career.
"I hope to continue developing as a player here. Together with the team, we'll do everything we can to compete for trophies."
Mofokeng will wear the No. 38 jersey, the same number he sported during his rise at Orlando Pirates.
The Sharpeville-born winger began his football journey with Sharpeville Juventus before joining the Transnet School of Excellence. He later moved to Pirates, where he progressed through the DStv Diski Challenge ranks before earning promotion to the senior team in 2023.
Since making his first-team breakthrough, Mofokeng has established himself as one of South Africa's brightest young talents, making 125 appearances for the Buccaneers while scoring 29 goals and providing 31 assists.
His move to Union Saint-Gilloise marks another major milestone in a remarkable rise and gives him the opportunity to showcase his talent on one of European football's biggest stages.