High-quality nanostructure of dysprosium substituted nickel–cobalt ferrite and their composite with reduced graphene oxide (rGO) were synthesized. The structuraland photocatalytic properties of prepared samples were studied. The XRD and FTIR analysis confirmed the FCC spinel structure. The calculated average crystallite size of nanoparticles was around 7.8 nm. The bandgap energy of synthesized composition was found to be 2.27 eV. The uniform dispersion of nanoparticles on the graphene nanosheets were confirmed by the FESEM analysis. The photocatalytic efficiency of nanoparticles and their composites with rGO was studied for degradation of methylene blue (MB) under visible light irradiation. It was found that nanocomposite exhibited high photocatalytic activity (72.7%) as compared to Dy+3 substituted Ni-Co ferrite nanoparticles (52.4%). This enhanced photocatalytic activity can be attributed to the presence of graphene, which enhances the stability of nanocomposite and reduces the recombination of charge carriers.