Herein,we report the synthesis of a non‐cytotoxic ternary ZnFe2O4‐CeO2/bioreduced graphene oxide (BRZC) nanocomposite via in situ reflux method using a green solvent. The bioreduced graphene oxide (BRGO) used in the nanocomposite was obtained by reducing graphene oxide (GO) in Ocimum tenuiflorum leaf extract. Thourough structural, morphological, and photochemical characterizations revealed that the BRZC heterojunction possesses highly crystalline nanoparticles, enhanced surface reactive sites and suitable band arrangement for photon adsorption. Such a structure was found to bebeneficial in accelerating photocatalytic reaction synergistically by inhibiting charge carrier recombination. The BRZC nanocomposite showcased superior efficiency towards Chlorpyrifos (0.0634 min−1) andRhodamine B (0.0907 min−1) photodegradation. Detailed investigations revealed a most suitable internal electric field‐driven direct Z‐scheme mechanism between ZnFe2O4 and CeO2,where BRGO acts as a cocatalyst. After multiple photochemical and radical trapping experiments, .OH and O2.− were found to be the active species behind the enahnced activity. The ternary heterojunction was also found to be effective for highly toxic real textile effluents with 82 % degradation efficiency. Moreover, Trypan Blue Exclusion (TBE) assay study demonstrated the non‐cytotoxicity nature of the photocatalyst and a significant decrease in cytotoxicity of the above photocatalytically treated pollutants.