INTRODUCTION: Microalgae and cyanobacteria are promising sources of bioactive compounds with antioxidant and anticancer properties. The cyanobacterium has been studied for its potential antioxidant, anti-inflammatory, antibacterial, antiviral, and anticancer effects. This study investigates its anticancer effects on colorectal cancer (CRC) at the cellular and molecular levels. METHODS: The metabolites of were screened using the Folin-Ciocalteu reagent and GC-MS. Antioxidant activity was assessed using the DPPH assay. The biological effects of methanolic extract (ME) were evaluated using MTT assay, Annexin V/PI staining, DAPI staining, and western blotting. Cells were treated with ME at concentrations ranging from 5 to 500 µg/mL for 24 and 48 hours, with the IC values determined at 373 µg/mL and 291 µg/mL, respectively. RESULTS: ME contained bioactive compounds such as phenols, flavonoids, and anthocyanins. Identified fatty acids included palmitic acid ethyl ester (15.53%), 1-bromo-11-iodoundecane (2.31%), undecanoic acid 2,8-dimethyl methyl ester (6.62%), oleic acid (6.47%), and 7-dehydrocholesterol (7.97%). ME inhibited SW480 cell proliferation in a dose- and time-dependent manner and induced nuclear fragmentation, chromatin remodeling, and apoptosis. Annexin V/PI staining confirmed apoptosis as the dominant mode of cell death. Western blot analysis showed increased Bax and decreased Bcl2 expression, supporting its pro-apoptotic activity. CONCLUSION: may serve as a potential therapeutic agent for gastrointestinal cancers through its ability to modulate the Bax/Bcl2 pathway and promote apoptosis. These findings highlight its novel anticancer effects and support further preclinical investigations.