99Tc is primarily released in spent nuclear fuel reprocessing, mainly exists as \({\text{TcO}}_{4}^{-}\) anions in aqueous solution, while its removal still remains a challenge due to its complex chemical behavior. Among various methods, adsorption stands out for its low cost and high selectivity. This review focuses on emerging nanomaterials, including covalent organic frameworks (COFs), metal–organic frameworks (MOFs), cationic polymer networks (CPNs), MXenes, layered double hydroxides (LDHs), and nano zero-valent iron (nZVI), for 99Tc removal through adsorption. The adsorption performance and mechanism of these nanomaterials for \({\text{TcO}}_{4}^{-}\) removal were critically reviewed. Additionally, these nanomaterials’ irradiation stability and reusability were also assessed. Finally, the challenges and future research directions are discussed, offering insights into enhancing the practical application of these materials for radioactive wastewater treatment.
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