Breydel, who was by trade a butcher, led the Bruges Matins together with Pieter de Coninck, a weaver, in May 1302. About three weeks before, on 1 May that year, they had partaken in an attack on the castle of Male and the complete annihilation of the French garrison there. The city archives of Bruges show that Jan Breydel was present from 8 July until 10 July 1302, in Kortrijk, as a supplier of meat for the troops. On the basis of this record, it is generally accepted that he had fought on 11 July 1302 in the Battle of the Golden Spurs.
In 1308, he helped to disengage Willem van Saeftinghe, who had fought on the same side at Kortrijk six years earlier, from the church of Lissewege where Willem had barricaded himself during an uprising.
Jan Breydel and Pieter de Coninck have often been portrayed as patriotic heroes in Belgium because of their passion for Flemish identity. Belgian nationalists (like the historian Henri Pirenne) used to claim they and the actions of their militia prevented Belgium from becoming an integral part of France early on. Flemish nationalists credit them with ensuring the survival of the Dutch language in the northern part of Belgium. Jan Breydel himself always regretted that the retrieval of Flemish autonomy meant giving up the French-speaking but culturally Flemish town of Lille, which was later reconquered by the Burgundians, but lost for good as a result of Louis XIV's annexation wars. The statue Jan Breydel shares with Pieter de Coninck has decorated the Market Place in Bruges ever since 1887.
In 2005 he was nominated on a shortlist of 100 famous Belgians for the title of De Grootste Belg (an election of the greatest person in Belgian history), but didn't make it to the final list, ending up at #35.