The green EDAS–(CuO–Ag) nanocomposite was synthesized using Syzygium cumini seed extract. S. cumini seed extract act as a reducing as well as stabilizing agent. The synthesized nanocomposites were characterized using different techniques such as UV–vis, FT‐IR, XRD, HRTEM, BET, and XPS. Photocatalytic activity was examined by subjecting it to UV light irradiation conditions and measuring its performance in degradation methylene blue. Additionally, the antibacterial activity of nanocomposite was assessed against Gram‐positive and Gram‐negative bacteria. The results revealed that the photocatalytic and antibacterial activities are in following order: CuO < CuO–Ag < EDAS–(CuO–Ag).