Due to high medicinal qualities, plants are being massively explored in scientific research, and in medical and pharmaceutical industries. Hence, the present study was conducted to determine the antioxidant, cytotoxic and antibacterial properties of Allium cepa Linn. The crude extracts of A. cepa L. showed significant antioxidant property via DPPH Free Radical Scavenging Assay and Iron Chelating Assay, of which ethyl acetate extract demonstrated the highest activity with EC50 value of 41.229 µg/ml and 55.419 µg/ml respectively. Folin-Ciocalteu Reagent Test and Aluminium Chloride Colourimetric Method also revealed the superiority of ethyl acetate in extracting phenolic compounds (70.10 µg GAE/mg) and flavonoids (101.28 µg QE/mg). The cytotoxic property of the extracts was tested on human chronic myelogenous leukemia cell line (K562) via 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) Assay. Ethyl acetate extract showed good cytotoxicity against K562 cells, having IC50 value of 131.46 µg/ml, 104.75 µg/ml, and 59.91 µg/ml at 24, 48 and 72 hours of incubation respectively. Qualitative screening on the antibacterial property of the extracts was carried out via Broth Microdilution Method. Ethyl acetate extract was again proved to exhibit inhibitory and bactericidal activity against Staphylococcus aureus, Enterococcus faecalis, Pseudomonas aeruginosa, and Escherichia coli.