Bacterial wilt of tomato is caused by the soilborn bacterium Ralstonia solanacearum (Rs). The disease is difficult to manage and produces serious yield losses. Natural products, such as plant extracts, represent new environmentally sustainable control strategies. The aim of this study was to evaluate the antibacterial efficiency of Melia azedarach bark extracts against the phytopathogenic bacteria Rs. Three bark extracts were performed using water and ethanol as solvents. The minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) of bark extract against Rs were defined using the broth microdillution method. Motility inhibition and changes in colony morphology were assessed, and bacterial survival was evaluated on humid substrate supplemented with different bark extract amounts. Bark extract affected the viability, colony morphology (where changes in the shape, cell density, and edge morphology of the colony were observed), and motility (with swarming motility reduced by 47.61% with ½ bark extract MIC, and 66.67% with bark extract MIC) on Rs. The application of the extract on the humid substrate controlled Rs in fewer amounts than MIC (0.176 g/l). Bacterial motility has been described as a key feature for pathogenicity in Rs. In this context, the inhibitory effect of M. azedarach bark extract on bacterial motility, and its bactericidal activity when applied on the substrate (where Rs survives between growing seasons), showed that this natural product is a promising tool to be used as an efficient sustainable strategy for the control of bacterial wilt of tomato.