AbstractLow‐ and high‐derivatives of magnetic starch nanoparticles (MSNPs) are obtained at respective 5 and 10 mL of 25% glutaraldehyde at 60, 70, and 80°C via coprecipitation of iron (II, III) oxide with jack bean starch. Their swelling power, solubility, bulk density, Fourier transform infra‐red (FTIR) patterns, thermogravimetric analysis (TGA)‐differential thermal analysis (DTA), x‐ray diffraction (XRD), Brunauer–Emmet–Teller (BET) properties, and morphology are analyzed. The results show that the MSNPs derivatives are pH‐responsive and temperature‐dependent. Peak swelling power (4.19 ± 0.01 g/g) of MSNPs derivative is obtained at 60°C. MSNPs derivatives are more soluble in acidic medium than alkaline medium. Bulk density improves three times more in MSNPs derivatives. FeO stretching bonds are observed at 530.73, 551.03, and 621.44 cm−1 for the MSNPs derivatives in addition to peaks of OH stretching at 3251.06 cm−1 (native starch [NS]), 3308.41 cm−1 (low‐substituted MSNPs), and 3133.28 cm−1 (high‐substituted MSNPs). The TGA‐DTA curves are endothermic and MSNPs are thermally stable beyond 700°C. MSNPs derivatives exhibit average lattice constant of 0.82382 nm with prominent peaks at 30.00° 2θ and 32.00° 2θ. MSNPs derivatives are mesoporous with peak BET surface area of 50.462 m2g−1. The microstructures of NS and MSNPs derivatives are predominantly oval. The MSNPs studied can serve as alternative functional biomaterials and nanosorbents.