<p>A series of multifunctional nanocomposites-CeO₂, CeO₂@Ag, and AC/CeO₂@Ag- were fabricated via a straightforward co-precipitation process and systematically characterized using XRD, FT-IR, UV-DRS, PL, FT-Raman, FE-SEM, HR-TEM, XPS, and EDX. XRD confirmed progressive crystallite size reduction from 35.64&#xa0;nm (CeO₂) to 30.53&#xa0;nm (CeO₂@Ag) and 28.46&#xa0;nm (AC/CeO₂@Ag), indicating nanoscale refinement induced by silver and activated carbon. FT-IR and EDX analyses validated successful functionalization and high oxygen content, while silver incorporation (5.68%) highlighted enhanced surface reactivity. The nanocomposites exhibited excellent dual functionality in photo catalysis and energy storage. CeO₂@Ag/ACachieved 97.82% UV-assisted degradation of alizarin red dye irradiation, outperforming CeO₂ (77.77%) and CeO₂@Ag (83.57%). This enhancement is resulting from the cooperative action of silver nanoparticles and activated carbon, which extend light absorption into the visible region, promote charge separation, and suppress electron–hole recombination. COD measurements confirmed efficient mineralization, underscoring environmental applicability. In addition of CeO₂ Nano sheet electrodes demonstrated a remarkable specific capacitance of 890.25 Fg⁻¹ with 96.2% retention after 1000 cycles at 1 Ag⁻¹, which is ascribed to the presence of engineered oxygen vacancies that enhance electron transport. These findings highlight CeO₂@Ag-based composites as promising multifunctional materials for environmental remediation, energy storage, and biomedical applications.</p>