Efforts to develop new potent and effective antimicrobial compounds with lower side effects are important not only for controlling serious infections but also for cancer, surgical operations, and preventing possible infections which are related to other threats. Therefore, it is getting more important to develop new antibacterial and antifungal compounds with wide spectrum, systemic effect and lower side effects. In this study eight new 3(2H)pyridazinone derivatives were synthesized and their antimicrobial activities were evaluated by using broth microdilution method agains two Gr (+) (Staphylococcus aureus, Enterococcus faecalis), two Gr (-) bacteria (Pseudomonas aeruginosa, Escherichia coli) and three yeasts like fungi (Candida albicans, Candida krusei). Compound D-2a had the best antibacterial activity among the synthesized compounds. All compounds were more effective against the fungus than the bacteria. In this study, we performed molecular modelling studies to provide in depth understanding of their CYP51 inhibition. Antifungal susceptibility tests against standard Candida spp. including C. albicans revealed D(2a)as highly active compound. The molecular docking studies showed similarities in binding interactions in active site gorges of the enzymes with known inhibitors, such as VT1, fluconazole.