Copper magnesium phosphate (CuMgP) nanoparticles were successfully synthesized via a solution combustion method and investigated as a potential electrode material for energy storage applications. Structural analysis by XRD confirmed phase formation, while FT-IR and UV-DRS studies verified functional groups and optical properties. SEM–EDX results revealed homogeneous morphology and uniform elemental distribution of Cu, Mg, P, and O. Electrochemical measurements in 1 M KCl demonstrated well-defined redox behavior with diffusion-controlled charge storage (b ≈ 0.45). The Nyquist plot indicated low charge transfer resistance and favorable ion transport characteristics. Symmetric charge–discharge profiles confirmed good reversibility and electrochemical stability. These results highlight CuMgP nanoparticles as a promising candidate for advanced supercapacitor applications.