The capital region averaged more than 400 new daily infections, according to Sciensano’s latest data on Wednesday.
The curfew in Brussels, lasting from 10:00 PM to 6:00 AM, was imposed in late October and until 19 November.
The regional cabinet is set to formalise the decision on Thursday, the spokesperson added.
Wallonia also moved to extend its own regional curfew until the same date, with all provincial governors passing the measures on Wednesday.
Both Brussels and Wallonia decided to tighten the midnight curfew imposed a national level by the regional government in the light of the rapid spread of the virus in the country.
The move by both regions will see the expiration of their lockdowns coincide with the current deadline with all nationwide lockdown measures, including the closure of non-essential shops, of bars and restaurants, and the reduction of social contacts.