Caprock wettability is a fundamental control on the sealing capacity and integrity of subsurface energy storage systems. In CO₂ geological sequestration, a strongly waterwet caprock ensures high capillary entry pressures, effectively preventing CO₂ migration. However, increased pressure and brine salinity can weaken hydrophilicity and compromise long-term sealing. In underground hydrogen storage, caprocks generally remain waterwet, yet the high diffusivity of H₂ reduce capillary sealing efficiency and may induce wettability alteration due to microbial or redox processes. Repeated injection-withdrawal cycles further cause transient wetting-drying and hysteresis, altering interfacial structures and capillary behavior. Understanding these dynamic wettability responses under varying physicochemical conditions is crucial for assessing storage security. Future studies should integrate in-situ characterization and molecular modeling to reveal reactive and reversible wettability mechanisms, providing a unified framework for CO₂ and H₂ storage systems.