In the present study, a new nanocomposite of iron/cobalt oxides and magnetic nanoparticle doped with polyaniline (PANI-Co3O4@MNPs) was synthesized and subsequently, evaluated for its potential in decontaminating nitrate ions from ground water. Various important parameters such as pH, mass dosage, adsorption time, initial concentration, and temperature were experimentally investigated. The important surface and chemical properties of PANI-Co3O4@MNPs, such as surface morphology and roughness, composition and chemical structure were evaluated using field emission scanning electron microscope, energy-dispersive X-ray spectroscopy, and Fourier transform infrared. Finally, the removal of nitrate was assessed using kinetic, adsorption isotherm, and thermodynamic studies to investigate the underlying mechanism of the removal process. Maximum adsorption capacity was found to be 68.96 mg/g for nitrate ions at pH 6, adsorbent dosage 60 mg within 60 min. The kinetic studies and the adsorption isotherms have been well fitted using pseudo first and the Freundlich models respectively whereas the thermodynamic parameters have been described in terms of enthalpy, entropy, and Gibbs free energy which showed a negative value signifying that the adsorption process was exothermic and spontaneous in nature.