Plants are vital for life due to their various constituents, comprised of various parts like roots, stems, and leaves. Herbal medicines have been known to man for centuries. The study was designed to check and compare the antibacterial activity of onion (Allium cepa L.), neem (Azadirachta indica A. Juss.), and bitter gourd (Momordica charantia L.) methanolic extracts against four bacterial strains, Bacillus cereus, Bacillus subtilis, Escherichia coli, and Staphylococcus aureus. All bacterial strains were cultured on nutritional agar plates. Three parameters were used in this research: concentrations, pH, and temperature. The five concentrations, 50 mg/mL, 70 mg/mL, 90 mg/mL, 110 mg/mL, and 130mg/mL were applied to all bacterial strains. At 110mg/mL, the methanolic extract of neem and bitter gourd applied to E.coli and S. aureus showed the largest zone of inhibition of 1.8 mm. The minimum inhibitory concentration (MIC) for Bacillus subtilis was 50 mg/mL when onion methanolic extract was applied. Onion and neem extract was found effective at 100 0C against E.coli and B. subtilis, while bitter gourd controls the growth of E.coli at 60 0C. The results of variable pH revealed that onion and bitter gourd were effective at pH 7 against B. subtilis, while neem was effective against S. aureus at pH 2. The results of the present study suggest that all onion, neem, and bitter gourd extracts have compounds containing antibacterial properties that can potentially be useful to control food-borne pathogens. By comparing the extracts of selected plants, neem was found to be more effective than onion and bitter gourd.