<p>Unitized regenerative fuel cells (URFCs) integrate fuel-cell and water-electrolysis modes within a single stack, enabling compact and reversible energy storage systems. Bipolar plates are key components that serve as current collectors, gas separators, flow-field supports, and structural elements, and strongly influence stack weight, volume, and ohmic losses. Conventional carbon-based plates offer low density and high electrical conductivity but are prone to carbon oxidation at the high anodic potentials used in electrolysis, leading to increased porosity, surface degradation, and elevated interfacial contact resistance. Metallic plates, particularly titanium and stainless steel, provide superior mechanical strength, reduced thickness, and excellent gas impermeability. However, oxide layer formation on their surfaces necessitates the use of conductive protective coatings to maintain low contact resistance and long-term stability under alternating redox conditions. Recent advances have focused on hybrid metal–carbon bipolar plates that combine the advantages of both material classes. These include bulk metal–carbon composites, metal substrates with carbon-rich or noble-metal coatings, and nanostructured composites incorporating carbon nanotubes or graphene networks. In these systems, performance is governed by the interplay of composition, microstructure, and surface engineering rather than any single material property. The central design strategy is hybridization: carbon components reduce mass and enhance conductivity and hydrophobicity, while metallic phases improve mechanical robustness and corrosion resistance. This review summarizes material systems, fabrication strategies, microstructural control, and corrosion mechanisms, highlighting that compositionally optimized and surface-engineered hybrid bipolar plates offer a promising route toward durable, high-performance URFC stacks.</p> Graphical abstract <p></p>