Their own Regenboog (Rainbow) Stadium, with a capacity of 8,500, does not meet UEFA criteria to enter the competition in the third qualifying round.
Zulte Waregem chief executive Patrick Decuyper said they hoped to sell out the 28,000-capacity Constant Vanden Stock Stadium in the Belgian capital.
"We are reckoning on 15,000 Zulte Waregem supporters and hope that neutrals from Brussels and elsewhere will come too. It depends, naturally, on who we draw," he told the club website.
Zulte Waregem missed out on a first Belgian title by two points to Anderlecht on the last day of the season in May.
It was their best finish in the Belgian league and this will be their Champions League debut.
The draw for the third qualifying round will be held on July 19 and possible opponents for Zulte Waregem include former European Cup winners PSV Eindhoven, Turkish club Fenerbahce or Olympique Lyon from neighbouring France.
- Sports & Recreation