Alderweireld, 34, drilled the ball into the top corner from outside the area in injury time as Antwerp secured their first league title in 66 years.
The draw moved Antwerp a point above Genk in second and third-placed Union Saint-Gilloise, who lost 3-1 at home to Club Brugge on a thrilling final day.
"I've experienced a lot of emotions in my career but this one goes above them all," said Alderweireld, who won 127 caps for Belgium.
Mark van Bommel's side will have to play in qualifying for next season's Champions League after Belgium's UEFA co-efficiency ranking slipped.
June 4, 2023