“Update of the giant hogweed (Heracleum mantegazzianum) distribution in Wallonia” is a presence/absence dataset focusing on giant hogweed in the Senne basin, ;collected from the field in June 2021 all over Wallonia, Southern Belgium. Historical sites where the species was recorded previously were re-visited by the Contrats de Rivière de Wallonie to assess the outcome of management actions conducted in the past. The dataset includes absence records and should be considered with caution. Data compilation, cleaning and validation were performed by the Département de l’Étude du Milieu Naturel et Agricole (SPW – DGARNE - DEMNA).