In the present study, Co₃O₄ nanocube-doped polyaniline nanocomposites have been successfully synthesised via an in situ oxidative polymerisation technique using ammonium persulfate (APS) as an oxidant in acidic medium for efficient removal of methyl orange (MO) from aqueous solution. Field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), thermogravimetric analysis (TGA), X-ray diffraction (XRD), Brunauer–Emmett–Teller analysis (BET) and Fourier transform infrared spectroscopy (FT-IR) measurements were used to characterise the prepared nanocomposites. The adsorption efficiencies of the PANI homopolymer and Co₃O₄ nanocube-doped nanocomposites were evaluated by monitoring the adsorption of methyl orange model dye from aqueous solution. The results revealed that the adsorption efficiency of the nanocomposites that were doped with Co₃O₄ nanocubes was higher than that of the undoped PANI and the adsorption kinetics followed a pseudo-second order reaction. Moreover, the nanocomposite with 4 wt% Co₃O₄ nanocubes with respect to aniline exhibited a superior adsorption capacity (107 mg g⁻¹) as compared to other absorbents.