In this study, a novel photocatalytic material heterostructured ZnO-CdO-CuO nanocomposite along with pristine ZnO, CdO, and CuO nanoparticles were synthesized by the facile co-precipitation method. The grown nanocomposite was characterized by XRD, FTIR, Raman, SEM, IV, UV–vis and PL techniques. The XRD pattern exhibited the diffraction peaks of ZnO (hexagonal), CdO (cubic) and CuO (monoclinic) with ZnO, CdO, and CuO phases 65%, 16%, and 19%, respectively. The microstructural analysis was carried out using Scherrer plot, W-H and SSP methods. The FTIR and Raman spectra also inveterate the successful formation of ZnO-CdO-CuO. The IV measurements revealed the high electrical response of nanocomposite. The SEM images are shown agglomerated rod-shaped morphology and the elemental analysis also confirmed the higher atomic concentration of Zn. PL spectra shown strong NBE and DLE emissions related to extrinsic defects which could act as the trap centers for charge carriers and enhance photocatalytic activity. The energy bandgap (Eg) was 2.9 eV, specified that the grown nanocomposite could be an excellent photocatalyst. The photocatalytic activity was performed against methylene blue (MB) revealed higher degradation efficiency of 94% as compared to pristine ZnO (60.0%), CdO (41.0%), and CuO (61.0%). The photodegradation of other synthetic dyes i.e. rhodamine-B, methyl orange, and cresol red was also assessed by grown nanocomposite under sunlight, exhibits degradation efficiencies, 87%, 89% and 99% in 100 min illumination, respectively. Furthermore, the species trapping experiment along with the recyclability test was carried out against cresol red dye using the nanocomposite catalyst. A schematic model was also designed to illustrate the photodegradation reaction mechanism. Display omitted •A novel heterostructured ZnO-CdO-CuO nanocomposite was synthesized.•Enhanced photocatalytic activity of nanocomposite against MB dye than pure oxides.•CR dye was degraded more as compared to MB, RhB and MO dye under similar conditions.•The main role of O2*- and HO* radicals in degradation reaction.•The PL spectra shown NBE and DLE were due to intrinsic defects.