The blaze erupted on the main stage, sending thick smoke across nearby woodland. While the cause remains unclear, technical teams on-site were safely evacuated and no injuries were reported.
The fire has cast uncertainty over the weekend's headline performances, but organisers say preparations continue.
Local authorities advised residents to stay indoors due to the smoke. DreamVille, the festival campsite, is expected to open as planned.
Despite the setback, the Tomorrowland team remains determined to deliver the show.
Tomorrowland, held each July in Boom, Belgium, is one of the world's biggest and most iconic electronic music festivals, known for its massive crowds, spectacular staging and a diverse lineup of top international DJs across multiple EDM genres.
