Aim: To investigate the role of biofilm-forming Paenibacillus polymyxa strains in controlling crown root rot disease. Methods and Results: Two plant growth-promoting P. polymyxa strains were isolated from the peanut rhizosphere, from Aspergillus niger-suppressive soils. The strains were tested, under greenhouse and field conditions for inhibition of the crown root rot pathogen of the peanut, as well as for biofilm formation in the peanut rhizosphere. The strains' colonization and biofilm formation were further studied on roots of the model plant Arabidopsis thaliana and with solid surface assays. Their crown root rot inhibition performance was studied in field and pot experiments. The strains' ability to form biofilms in gnotobiotic and soil systems was studied employing scanning electron microscope. Conclusion: Both strains were able to suppress the pathogen but the superior biofilm former offers significantly better protection against crown rot. Significance and Impact of the Study: The study highlights the importance of efficient rhizosphere colonization and biofilm formation in biocontrol.