An excellent fit between the theoretical and experimental studies of the related to structure, optics, and magnetism features of pristine and cerium-modified Zn-O NPs prepared through the wet chemical technique. Refining the XR-D pattern using the Rietveld-method reveals that the samples have a hexagonal Wurtzite structure. Absorption spectra reveal a shrinking bandwidth gap as cerium doping increases, substantiating ce2+ ion's essential function in ZnO's spectral qualities. The narrowing of the bandwidth gap due to the presence of impurity states was also verified by first-principles calculations. The residual magnetization increases with Cerium doping, and magnetic tests show roomtemperature weak-ferromagnetism (RTFM). In addition, ferromagnetism for cerium doping is confirmed by both first-principles calculations and experiments. Theoretical calculations imply that the cerium atoms may agglomerate to generate metallicantiferromagnetic chromium oxide when cerium doping reaches 8%. At ambient temperature, however, ferromagnetic behaviour is feasible since both ferromagnetic and antiferromagnetic behaviour are degraded when cerium is widely disseminated throughout the lattice as revealed by XRD studies