New hydrazone derivatives were synthesized via the nucleophilic addition–elimination reaction of 2-[(1-methyl-1H-tetrazol-5-yl)thio)]acetohydrazide with aromatic aldehydes/ketones. The compounds were tested in vitro against various Candida species and compared with ketoconazole. Genotoxicity of the most effective anticandidal compounds was evaluated by umuC and Ames assays. All compounds were also investigated for their cytotoxic effects on NIH3T3 and A549 cell lines. Compound 8 was the most effective antifungal derivative against C. albicans (ATCC-90028) with a MIC value of 0.05 mg/mL. Compound 5 can be identified as the most promising anticancer agent against A549 cancer cell lines due to its inhibitory effect on A549 cell lines and low toxicity to NIH3T3 cells.