Display omitted •Novel direct dual-Z-scheme ZnO-Er2O3-Yb2O3 heterostructured nanocomposite synthesized by simple co-precipitation method.•Photocatalytic and antibacterial application study.•The effect of several operational parameters on photocatalytic activity was studied.•The conventional hetero-junction scheme and direct dual-Z-scheme were proposed to elaborate the photocatalytic mechanism. In this work, a novel antibacterial and photocatalytic material ZnO-Er2O3-Yb2O3 heterostructured nanocomposite was synthesized by facile co-precipitation technique. The antibacterial activity was performed against S. aureus and E. coli bacteria. The ZOI showed the nanocomposite has higher activity antibacterial against E. coli. The direct optical energy bandgap was 2.9 eV, specified it as a proficient photocatalyst under sunlight illumination. The grown nanocomposite degraded 99.7% MB dye in 40 min under sunlight irradiation. The effect of several operational parameters including catalyst dose, dye concentrations, pH of reaction along with reusability and radical trapping experiment was also studied. The conventional hetero-junction scheme and direct Z-scheme were also proposed to elaborate the photocatalytic mechanism.