Abstract: Inorganic nanomaterials are typically considered to be biologically inert. However, recent studies have shown that some types of inorganic nanomaterials exhibit catalytic activities similar to that of natural enzymes. We named this type of nanomaterials with enzyme-like activity as nanozyme. The finding of nanozyme breaks the traditional cognition of enzyme, and nanozyme is emerging as a new field of enzymology. Moreover, as a natural spherical nanostructure with uniform size, ferritin can be easily engineered to novel types of nanozymes. Importantly, natural ferritin can specifically target to many types of tumor cells without any modifications, which makes it as a promsing nanocarrier for tumor therapy. In this review, we briefly introduced the concepts of nanozymes and ferritin, and summarized our recent studies on nanozyme and ferritin in the fields of environmental management, immunoassay and tumor diagnosis and therapy. In addition, we gave prospects of nanozyme in biomedicine in the near future.