Surface wettability plays a critical role in governing interfacial phenomena of nuclear fuel cladding, particularly under boiling and corrosion-driven environments. In this study, we introduce a surface engineering process to render the Zirlo cladding alloy superhydrophilic, addressing its inherently limited interfacial performance in coolant environments. A nanoporous ZrO 2 oxide layer was formed via electrochemical anodization, and the pore size was systematically controlled by varying the applied voltage (30–90 V). The anodized samples exhibited a significant reduction in contact angle, showing superhydrophilic behavior (<10°) compared to the bare alloy (∼79°). Among the tested conditions, the sample anodized at 30 V, which possessed the smallest pore size, exhibited the lowest contact angle of approximately 7.5°. Structural and chemical analyses revealed that the enhanced wettability originates from the synergistic contribution of increased surface hydroxylation and nanoporous morphology. While hydroxyl groups improve intrinsic hydrophilicity, the nanoporous structure promotes capillary-driven liquid infiltration and roughness-induced amplification, collectively enabling the transition to a superhydrophilic state. Notably, this highlights that nanoporous geometry provides a critical wetting mechanism beyond conventional surface chemical modification. From a nuclear application perspective, the resulting surface is expected to promote stable hydration at the cladding–coolant interface, potentially suppress vapor nucleation and enhance rewetting, thereby contributing to the mitigation of CRUD deposition. These findings suggest that nanoporous surface engineering offers a practical and scalable strategy for improving the interfacial performance of nuclear cladding materials, with potential applicability to a wide range of industries requiring controlled surface properties.