Recent advances in the development and biological applications of polymeric nanomaterials embedded with superparamagneticironoxide nanoparticles (SIONPs) are summarized. Novel SIONP-polymer hybrid nanoparticles are prepared by various methods, including direct modification with polymers, surface-initiated controlled polymerization, inorganic silica/polymer hybridization, self-assembly, self-association, and various heterogeneous polymerization methods. They have potential for various biomedicalapplications, including magnetic resonance imaging (MRI) contrast enhancement, targeted drug delivery, hyperthermia, biological separation, protein immobilization, and biosensors.