We demonstrated the efficacy of magnetic nanoparticles (MNPs) produced from a low grade iron ore as an adsorbent for the removal of Cr(VI), a toxic heavy metal anion present in wastewater. The adsorption of Cr(VI) by these MNPs strongly depended on the dosage of MNPs, the initial concentration of the Cr(VI) solutions, and pH. The highest Cr(VI) adsorption efficiency of 22.0 mg/g was observed at pH 2.5. The adsorption data were best fit with the Langmuir isotherm and corresponded to a pseudo‐second‐order kinetic model. The used adsorbent was regenerated by eluting in highly alkaline solutions. Sodium bicarbonate showed the highest desorption efficiency of 83.1% among various eluents including NaOH, Na2HPO4, and Na2CO3. Due to the high adsorption capacity, the simple magnetic separation, and the high desorption efficiency, this nano‐adsorbent produced from inexpensive and abundant resources may attract the attention of the industries to apply for removing various metal anionic contaminants from wastewater. Keywords：Adsorption; Magnetic nanoparticles; Iron ore tailing; Chromium; Wastewater