The purpose of this study was to examine the nitrate adsorption by cobalt ferrite (CFO) nanoparticles. The adsorbent was synthesized by co-precipitation method and its structure was characterized using Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), Fourier Transform Infrared Spectroscopy (FTIR), X-ray diffraction (XRD) and Vibrating-Sample Magnetometer (VSM). In batch adsorption studies, the effects of various parameters like pH (3–11), adsorbent dose (0.2–0.8 g/L), contact time (5–120 min), initial nitrate concentration (50–200 mg/L), and temperature (283–313 K) on the adsorption process were examined. The results of this study indicated that the maximum adsorption capacity was 107.8 mg/g (optimum condition pH = 3, adsorbent dosage: 0.2 g/L, nitrate concentration: 200 mg/L, contact time: 20 min and temperature 313 K). The adsorption isotherm had a proper match with Langmuir (R2 = 0.99) and Freundlich (R2 = 0.99) models. The adsorption of nitrate by CFO has followed pseudo second-order kinetics. The results of the thermodynamics of the nitrate adsorption process by CFO showed that all the values of ΔG, ΔH and ΔS were positive. Therefore, this process was endothermic and non-spontaneous.