The increasing prevalence of antibiotic resistance and the emergence of novel pathogenic strains emphasize the need to investigate medicinal plants as accessible and cost-effective sources of potential antimicrobial agents. Species of Amaranthus have been used in traditional medicine for the treatment of various ailments. This study aimed to assess the in vitro antimicrobial effects of various extracts from the aerial and underground parts of Amaranthus blitum subsp. oleraceus. The extracts were tested for their effects on diverse microbial populations, including Gram-positive and Gram-negative bacteria, as well as Candida albicans, using the disk diffusion method. Crude ethanolic, acetonic, benzene and chloroform extracts were dissolved in 100% DMSO, while aqueous extracts were dissolved in distilled water to prepare stock solutions, which were adjusted to a concentration of 75 mg/mL for subsequent analysis. The results indicated that ethanol, acetone, and chloroform extracts from both aerial and underground parts exhibited antibacterial activity, particularly against Bacillus anthracoides, while ethanolic, acetonic, benzene, and chloroform extracts of both parts showed antifungal activity against C. albicans. All tested aqueous extracts exhibited very low antibacterial activity and did not show antifungal effect against C. albicans. A. blitum subsp. oleraceus has been cultivated as a vegetable crop for centuries in diverse regions worldwide. The observed antibacterial activity of its crude extracts indicates the presence of bioactive constituents, supporting the need for further phytochemical investigations and potential applications in both pharmacological and agricultural fields.