The study aimed to synthesize phycocyanin-mediated silver nanoparticles (Ag-CNPs) using pigment extracts from Synechococcus BDUSM13 as a green nano-synthesis procedure, an alternative for the toxic chemical route. Biosynthesized Ag-CNPs were characterized and analyzed for their therapeutic (e.g. antibacterial) and biomedical (e.g. anticancer) potential. Ag-CNPs were spherical in shape, crystalline, and small width-to-length ratio with a 4 nm to 20.9 nm diameter range. They also unveiled a wide range of inhibition spectrum activity against clinical bacterial strains such as Campylobacter sp., Shigella sp., Salmonella typhi, Bacillus subtilis, and Klebsiella sp. Ag-CNPs showed the highest inhibition against Klebsiella (13.5 mm) and B. subtilis (13.3 mm) strains whereas the lowest zone of inhibition was observed against Shigella (8.0 mm) at 100 μg/mL Ag-CNPs. The cytotoxic analysis on the MDAMBA- 231 cancer cell line revealed that the proliferation rate was declined gradually with higher Ag-CNPs concentrations. The viability of cancer cells was also reduced from 80.15% to 29.12%, 41.42% to 18.12%, and 25.12% to 5.5%, respectively, after 24, 48, and 72 hrs of incubation. Quantitative verification of reactive oxygen species showed a 195.4% increase in ROS production with 38.9 μg/mL of Ag-CNPs in comparison to control cells. The study indicates that due to the strong antibacterial and anti-cancerous activity of Ag-CNPs, it could be employed as a novel antimicrobial and anticancer agents.