Marking the second protest of its magnitude in less than a year, protesters have criticized the center-right government's labor policies. The demonstration was marred by violence when 200 protesters clashed with police.
More than 80,000 people on Wednesday took to the streets of Brussels to protest austerity measures implemented during the first year of the center-right coalition government's tenure.
The protest marks the second of its size within a year, with the last one occurring in November 2014.
Three of Belgium's main unions joined the protests on a common platform that renounced policies implemented by the center-right government under the leadership of Prime Minister Charles Michel.
The protest was a response to what unions said were cuts in social services and tax measures aimed at benefiting employers.
The unions also cited an increase in retirement age along with a freezing of the link between wages and inflation.
While police estimated that more than 80,000 people participated in Wednesday's protest, organizers said they mobilized around 100,000 participants, just shy of last year's 120,000 demonstrators.
However, similar to November's demonstration, Wednesday's protest was marred by violence when around 200 protesters clashed with police.
At least three people were arrested and one officer injured, DPA news agency reported.
Police responded to the attack by using tear gas and water canons.
ls/sms (AP, dpa)