In this study, a novel method based on the magnetic Fe/C crosslinked nanoparticles (MNZVI/CNTs-OH) is reported for the effective removal of Cr(VI) in aqueous solutions. Parameters that influence the effectiveness of the nanoparticles, such as pH, temperature, reaction time, and particle dosage, was analyzed. It was found that MNZVI/CNTs-OH particles exhibit significantly higher activity toward Cr(VI) removal than bare NZVI, carbon nanotubes (CNTs), and other synthetic nanomaterials. Under optimized conditions, the removal efficiency of Cr(VI) by MNZVI/CNTs-OH is up to 98% with an initial contaminant concentration of 50 mg/L, and chromium content in the residue up to 48 mg/g. Physical characterizations, including Fourier transform infrared (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), and TG-TD measurements, provide insights into the working mechanism of Cr(VI) purification. Our findings suggest that immobilization of MNZVI onto carbon nanotubes increase the covalent bond property, while crosslinked nanoparticles (NPs) provide the electron transfer passage from the NZVI surface and improves the dispersity of the MNZVI, thus enhancing the performance. These results demonstrate the potential of the MNZVI/CNTs-OH nanoparticles for the rapid and efficient treatment of Cr(VI)-containing wastewater.