The main aim of this study was to ascertain the removal of chromium ions from synthetic wastewater using modified maghemite nanoparticles (MNPs). Commercially available maghemite nanoparticles (NPs) (< 50 nm) were modified using sodium dodecyl sulfate (SDS). The MNPs were characterized using a powder X-ray diffractometer (XRD) and Fourier transform infrared spectrophotometer (FTIR). Statistically designed batch experiments were carried out to evaluate the effects of various parameters, namely the pH of the solution, initial chromium concentration, and adsorbent dose, on the chromium removal efficiency (RE). The results from this study showed that the adsorbent dose had a synergistic effect on chromium RE, while pH and initial chromium concentration had antagonistic effects on the RE. An optimal chromium RE of 95.8% was obtained at pH = 2.6, adsorbent dose = 5 g/L, and initial chromium concentration = 20 mg/L. The analysis of variance (ANOVA) results showed that the model was significant, with high F value (F = 80.07) and low P value (P = < 0.001). Based on the results obtained from the experiments, the MNPs could be exploited as an efficient adsorbent for chromium removal from wastewater.