Abstract Construction of drug carriers or prodrugs is a common approach to improve the pharmacokinetics of molecular drugs and enhance the tumor curative effect. Nanocarriers that can be activated by the tumor microenvironment including enzymes, pH, redox status, or external stimuli such as ultraviolet, ultrasound, and magnetism, are booming. As a commonly used clinical theranostic approach with excellent spatiotemporal controllability and deep tissue penetration, X‐ray has attracted much attention as an external stimulus in recent years. The rapid development of nanomaterials as radiosensitizers or radioluminescents further accelerates the construction of X‐ray‐responsive nanocarriers. In this review, the currently developed X‐ray activated drug release systems in cancer therapy are summarized with a focus on controlled release design.