Molybdenum trioxide nanoparticles were synthesised via a simple and cost-effective solution combustion method. XRD confirmed an orthorhombic crystalline phase with an average crystalline size of 56.6 nm. UV-Vis spectroscopy indicated a direct bandgap of 2.9 eV, while RAMAN spectra revealed Mo = O and Mo-O stretching vibrations. SEM-EDAX analysis confirmed nanoscale morphology and a uniform Mo-O distribution. Photocatalytic studies, under direct sunlight, degraded 92% methylene blue dye within 120 min, following pseudo-first-order kineticsS. Furthermore, dose-dependent antibacterial activity was exhibited against E. coli and S. aureus. These findings highlight MoO3 NPs for sustainable agriculture by degrading pollutants and controlling microbes in irrigation systems.