This study developed and characterized the chitosan-functionalized Fe3O4@SiO2 nanoparticles (Fe3O4@SiO2@CS NP) as a drug delivery system. Fe3O4 NP were first synthesized by co-precipitation method, followed by coating with SiO2, and functionalized with chitosan via glutaraldehyde crosslinking bridges. The newly synthesized Fe3O4@SiO2@CS NP possessed an octagonal shape with a diameter of ~ 20 nm. In the FT-IR spectrum, the Fe3O4@SiO2@CS NP demonstrated the appearances of C–O, N–H, and C–H peaks, indicating the presence of chitosan in their structures. The Fe3O4@SiO2@CS NP could preserve the Fe3O4 magnetic property with a magnetization value of 52.43 emu/g, a magnetization remanence of almost 0 emu/g, and minimal residual coercivity. Utilizing curcumin as a drug model, the Fe3O4@SiO2@CS NP could adsorb the drug rapidly, to more than 71% within 20 min, with an adsorption capacity of 6.54 mg/g and an adsorption energy of 0.2029 kJ/mol (following the Dubinin–Radushkevich model). The curcumin adsorption process was in good agreement with the pseudo-second-order kinetics (R2 = 0.9975). Interestingly, in the simulated body fluid, the curcumin-loaded Fe3O4@SiO2@CS NP could retain the curcumin release, with no detectable drug release, in the first hour, followed by a burst release within the next hour. This confirms the contribution of CS in the system. Conclusively, the Fe3O4@SiO2@CS NP could be further developed to potentially become a controlled-release drug delivery system.