The rise of multidrug-resistant bacterial strains has created an urgent need for alternative antimicrobial agents. In this study, we report the green synthesis of mesoporous Ag@ZnTiO_₃ nanocomposites using ethanolic leaf extract of the Gaga plant. The synthesized materials were characterized for structural and morphological features and evaluated for antibacterial activity against both Gram-positive and Gram-negative bacteria. The antibacterial performance of the mesoporous Ag@ZnTiO₃ nanocomposites was evaluated against both Gram-positive Staphylococcus aureus and Gram-negative Escherichia coli bacteria using disk diffusion and minimum inhibitory concentration (MIC) methods. Mechanistic insights revealed that the antibacterial mechanism involves reactive oxygen species (ROS) mediated oxidative stress, membrane disruption, and inhibition of cellular processes, leading to bacterial cell death. Mesoporous Ag@ZnTiO₃ nanocomposites demonstrate excellent antibacterial efficacy and stability, making them a promising candidate for next-generation antimicrobial agents in medical and environmental applications. In addition, a One-way ANOVA study revealed that the plant-synthesized nanocomposite exhibited a significantly greater antibacterial effect on the Gram-negative bacterial strain compared to the Gram-positive strain. The p-values less than 0.05 (p < 0.05) indicate the statistical significance of the model terms. Further studies on scalability and long-term safety are recommended to pave the way for practical implementations.