Superparamagnetic iron oxide (SPIO) nanoparticles have become a popular strategy of cancer treatment and molecular imaging because of their versatile properties and biocompatibility. A variety of studies have shown the exciting potential of functionalized SPIO nanoparticles, such as surface-coated, targeted ligandconjugated, and/or drug-loaded SPIO nanoparticles, as powerful tools for targeted imaging and therapy. Moreover, the applications of SPIO nanoparticles that integrate diagnosis and therapy in SPIO nanoparticles facilitate the monitoring of therapeutic efficacy during treatment. In the present review, we primarily concentrate on the recent advancements in the field of SPIO nanoparticles in terms of synthesis, targeted therapy, and cancer imaging.