A series of ternary Cu@CuO–g-C₃N₄/MCM-41 photocatalysts have been synthesized by varying the percentage of Cu using simple impregnation and co-condensation methods. The physico-chemical characterization of all the samples was determined using XRD, FTIR, UV-Vis DRS, PL, N₂ ads–des studies, SEM and XPS HRTEM, EDAX, EIS and MS. The structural advantages of MCM-41, allow the uniform distribution of g-C₃N₄ and coexistence of Cu²⁺ along with Cu⁰ without using a reducing agent. The presence of g-C₃N₄ helps to shift the Fermi level of CuO towards more negative values due to accumulation of photogenerated electrons on the surface. It favours charge separation by creating a Schottky barrier at the junction. The 4 wt% Cu loaded over g-C₃N₄/MCM-41 exhibits a maximum 750 μmol 2 h⁻¹ of H₂ evolution under visible light irradiation with an apparent energy conversion efficiency of 24.8%. The enhancement in catalytic activity has been explained on the basis of synergism between g-C₃N₄ and Cu²⁺ and the SPR effect of Cu which also acts as a co-catalyst present on the surface of photocatalysts.