<p>In this paper, we discuss the fabrication and characterization of a novel composite photocatalyst, poly(m-aminophenol)/reduced graphene oxide/cobalt oxide (PmAP/rGO/Co₃O₄), and its incomparable photocatalytic efficacy towards the degradation of cationic dyes under the exposure of visible light. The composite was synthesized via an in situ oxidative polymerization method, utilizing rGO and Co₃O₄ as templates. The effect of varying rGO/PmAP percentages in the composite on photocatalytic performance was investigated, with 5 wt% rGO/PmAP (PRC-5) emerging as the most effective combination, exhibiting degradation percentages of 95.4% and 94.3% for methylene blue and malachite green, respectively, within 60&#xa0;min. The enhanced efficiency of the composite was attributable to the increased surface area and reduced cobalt oxide aggregation of nanoparticles, leading to enhanced light absorption. Photoluminescence (PL) spectra and Mott-Schottky data supported the proposed Z-scheme mechanism, which involved the generation of high concentrations of ^•OH radicals, holes (h⁺), and ^•O₂⁻, as revealed by the active species trapping experiment. Zone of inhibition for the <i>E. coli</i> bacterial strain as indicated by PmAP/rGO/Co₃O₄ NCs at a concentration of 1000&#xa0;mg/ml. It became apparent that the synthesized PmAP/rGO/Co₃O₄ conjunction was a highly effective antibacterial and photodegrading agent. Our findings suggest that the PmAP/rGO/Co₃O₄ composite holds great promise as an effective alternative for industrial wastewater treatment applications.</p> Graphical abstract <p>Graphical representation of dye degradation using poly(m-aminophenol)/reduced&#xa0;graphene oxide /cobalt oxide Catalyst</p> <p></p>