The natural bacterial communities of the soil–plant system are relevant in the process of suppressing diseases caused by soilborne plant pathogens. However, little is known regarding the structure of these communities in soils cultivated with brassica vegetables and their relationship with clubroot severity, a disease caused by Plasmodiophora brassicae. In the present study, the composition of bacterial communities in soils cultivated with cauliflower with distinct levels of disease severity was compared. The bacterial composition in soils with lower and higher clubroot severity differs in phylum and genera levels. Soils associated with plants with lower disease severity showed predominance of Kaistobacter, Flavisolibacter, Sphingobacterium, Koribacter, Nitrospira, Bradyrhizobium and Bacillus. Our study reinforces the importance of management strategies that promote improving the physical–chemical characteristics of soil, which are essential to modulate bacterial populations correlated with plant disease suppression.