TNF and neoplasm: In summary, we engineered an intratumoral microbiota metabolism‐engineered nanocomposite (Nb2C/Au/anti‐TNFα‐PVP) for regulating the abundance and diversity of a commensal microorganism and disrupting the metabolic pathways of intratumoral microbiota and tumor microenvironment associated with the types and levels of metabolites and biosynthetic substances that tumor growth demanded.