Abstract: Background and Objective: Microalgae are the vital constituents in food chains of aquatic ecosystems and have been used for human consumption as food and as medicines. The wide diversity of compounds synthesized from different metabolic pathways of fresh water algae provides promising sources of secondary metabolites in the form of phytochemical constituents. These metabolites are very interesting source of producing an herbal medicine to treat diseases like cancer which is a major public health concern. The study aims to determine the phytochemical constituents, antioxidant and anti-cancer activities of Tetradesmus acuminatus algal extraction MCF-7 human breast cancer cell line. Materials and Methods: The dried and dehydrated algae biomass was subjected to extraction by cold maceration method using 5 solvents of increasing polarity from a non-polar (hexane) to a more polar solvent (aqueous). Phytochemical screening was done using different biochemical tests. Quantitative analysis for phenol was determined by Folin-Ciocalteu reagent method. The antioxidant activity was tested using 2, 2-diphenyl-1-picrylhydrazyl, ferric ion reducing power assay. In vitro anti-cancer activity on MCF-7 human breast cancer cell line was evaluated by (3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide) MTT assay. Results: The phytochemical analysis revealed broad spectrum of bioactive compounds including flavonoids, glycosides, phenols, tannins, fats and oils. Methanol and aqueous extracts exhibited higher phenolic content as compare to ethanol extract. Antioxidant capacities were shown highest in methanol and ethanol aqueous based on the test performed. The methanol and aqueous extracts were found to be selectively cytotoxic in vitro to on MCF-7 human breast cancer cell line with IC50 values 468.31±24.15 and 598.12±12.18 μg mL–1 for MCF-7, respectively, while it had no cytotoxic effect on normal mice embryo fibroblast cells. Conclusion: The results indicate that Tetradesmus acuminatus was a promising antioxidant and anti-cancer agent for MCF-7 human breast cancer cell line. However, further studies are needed to conclude its therapeutic use.