In this work, graphene oxide nanosheets loaded by magnetic iron oxide nanoparticles (mGO) was synthesized and the technique of layer-by-layer (LbL) self-assembly was utilized in the successful production of chitosan/sodium alginate functionalized mGO naocomposites for use in targeted anti-cancer drug delivery and photothermal therapy. The mGO-CS/SA nanocomposites had a diameter of ˜0.5 μm and a thickness of 40-60 nm with superparamagnetic behavior. The modified nanocomposites exhibited a decrease in agglomeration and an increase in stability in biological solution following stability tests. Meanwhile, the nonspecific protein adsorption was strongly suppressed after the modification. The mGO-CS/SA nanocomposites were loaded with doxorubicin hydrochloride (DOX) via π-π stacking and electrostatic attraction with a high drug loading amount (137%, w/w). The DOX-loaded nanocomposites (mGO-CS/SA-DOX) showed improvements in function including enhanced dispersion and noticeable pH-sensitive drug release behavior. Cellular studies denoted magnetically targeted cellular uptake characteristics and excellent photothermal effect of mGO-CS/SA, as well as concentration-dependent cytotoxicity of mGO-CS/SA-DOX. Therefore the functionalization of mGO using chitosan and sodium alginate would be beneficial in biomedical applications.