The integration of local radiation therapy (RT) with transcatheter arterial chemoembolization (TACE) can effectively manage unresectable hepatocellular carcinoma (HCC). Nonetheless, achieving effective synergistic treatment efficacy by controlled on-dem, radiosensitization following TACE remains a significant issue. A nanoradiosensitizer-Lipiodol formulation (DSeSeP-API(Lip)) is developed using Touch-, -Go following X-ray irradiation (X-tag) for the theranostics of HCC. The nanoradiosensitizer (DSeSeP-API) is fabricated by conjugating ultrasmall AuPtICG (API) nanoparticles featuring an amphiphilic polymer with X-ray responsive diselenide motif (DSPE-Se-Se-PEG-SH), satisfying the ‘3s’ properties: 1) stable in Lipiodol; 2) sensitive to X-ray; 3) phase-shift from Lipiodol to the aqueous physiology. The homogeneous, stable lipiodol formulation is subsequently prepared via our super-stable homogeneous intermixed formulation technology (SHIFT). Following the successful transcatheter arterial embolization (TAE), the subsequent RT program commences. The initial X-ray irradiation is administered concurrently with the cleavage of the diselenide bond to facilitate the phase transition of hydrophilic SeP-API from Lipiodol (1X-Tag). Secondary X-ray irradiation is applied at the peak cellular uptake of sensitizers for enhanced X-ray dynamic therapy (XDT) (2X-ray). The research illustrates the capability of the nanoradiosensitizer-Lipiodol formulation with the “X-tag” feature to amplify the synergistic TAE−XDT therapeutic effects while effectively minimizing adverse effects.