Herein, we demonstrated the excellent improvement in photocatalytic degradation performance of BiOCl upon facile heterogeneous decoration with an integrated Ni_0.5Zn_0.5Fe₂O₄@polyaniline nanocomposite for an organic pollutant, methyl orange dye (MO), under visible light irradiation. The physico-chemical nature of the heterogeneous nanocomposite was characterized by XRD, FTIR, HRTEM-EDX and XPS analyses. The tuning of the band gap and optical sensitivity of BiOCl using Ni_0.5Zn_0.5Fe₂O₄@polyaniline were measured by DRS, PL and EIS techniques. To validate the transformation of the BiOCl photocatalyst to a visible light active photocatalyst due to the incorporation of Ni_0.5Zn_0.5Fe₂O₄@polyaniline and to gain insight into the origin of the synergistic effect for dye degradation by the heterostructured nanocomposite, we explored the effects of process parameters such as catalyst dosage, initial dye concentration, pH and the presence of inorganic anions on the extent of photo degradation. To get more details about reaction kinetics, a kinetic model using non-liner regression analysis was developed and the validity of the model was tested by comparing the experimental values with the calculated data. Based on the intermediate product formation, identified by GC-MS, a probable degradation pathway and a mechanism based on the electrochemical behaviour of the developed catalyst and trapping experiments were also proposed.