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As available tools for crop disease management are scarce, new, effective, and eco-friendly solutions are needed. So, this study aimed at assessing the antibacterial activity of a dried leaf <i>Eucalyptus globulus</i> Labill. aqueous extract (DLE) against <i>Pseudomonas syringae</i> pv. <i>tomato</i> (<i>Pst</i>), <i>Xanthomonas euvesicatoria</i> (<i>Xeu</i>), and <i>Clavibacter michiganensis michiganensis</i> (<i>Cmm</i>). For this, the inhibitory activity of different concentrations of DLE (0, 15, 30, 45, 60, 75, 90, 105, 120, 135, and 250 g L⁻¹) was monitored against the type strains of <i>Pst</i>, <i>Xeu</i>, and <i>Cmm</i> through the obtention of their growth curves. After 48 h, results showed that the pathogen growth was strongly inhibited by DLE, with <i>Xeu</i> the most susceptible species (15 g L⁻¹ MIC and IC₅₀), followed by <i>Pst</i> (30 g L⁻¹ MIC and IC₅₀), and <i>Cmm</i> (45 and 35 g L⁻¹ MIC and IC₅₀, respectively). Additionally, using the resazurin assay, it was possible to verify that DLE considerably impaired cell viability by more than 86%, 85%, and 69% after <i>Pst</i>, <i>Xeu</i>, and <i>Cmm</i> were incubated with DLE concentrations equal to or higher than their MIC, respectively. However, only the treatment with DLE at 120 g L⁻¹ did not induce any hypersensitive response in all pathogens when treated bacterial suspensions were infiltrated onto tobacco leaves. Overall, DLE can represent a great strategy for the prophylactic treatment of tomato-associated bacterial diseases or reduce the application of environmentally toxic approaches.