This study investigated the antibacterial properties of Pleurotus ostreatus (Jacq. Ex Fr.) P. Kumm. extracts against various pathogenic bacteria. The fruiting bodies of fresh oyster mushrooms were collected from Mae Phai Boon Mushroom Farm in Ban Thung Nang Rao, Mueang District, Mahasarakham Province, and subjected to extraction using 95% ethanol and 95% ethyl acetate solvents. The effectiveness of the extracts in suppressing the proliferation of pathogenic microorganisms, encompassing Bacillus cereus, Enterobacter cloacae, Escherichia coli, Proteus mirabilis, Pseudomonas aeruginosa, Salmonella typhi, Serratia marcescens, and Staphylococcus aureus, was assessed through the utilization of the paper disk diffusion technique. The results revealed that the crude extract obtained from the 95% ethanol solvent exhibited significant inhibitory effects against B. cereus, E. cloacae, P. aeruginosa, S. marcescens, and S. typhi, yielding inhibition zone diameters from 9.22 to 12.33 mm. In contrast, the crude extract from the 95% ethyl acetate solvent showed inhibitory activity only against E. coli, revealing an inhibition zone diameter of 12.00 mm. Additionally, the determination of the minimum inhibitory concentration (MIC) of the 95% ethanol crude extract against P. aeruginosa and S. marcescens established a value of 150 mg/ml, and concomitantly, the minimal bactericidal concentration (MBC) was also established at 150 mg/ml. However, it was observed that the 95% ethanol crude extract at a concentration of 15 mg/ml was incapable of suppressing the proliferation of E. coli in the MIC evaluations. These findings imply that the extracts originating from P. ostreatus possess inherent capacity as organic antibacterial agents targeting specific pathogenic bacteria. Therefore, these findings justify the necessity for additional scrutiny into their conceivable utilities within the domains of medicine and food preservation.