Abstract: With the vigorous expansion of the global marine economy and the rising strategic importance of the oceans, the shipbuilding industry is imposing ever-higher demands on next-generation, high-performance materials. High-entropy alloys (HEAs), distinguished by their unique multi-principal-element design paradigm and outstanding property profiles, are demonstrating broad applicability within marine engineering. In this study, a comprehensive review of recent advances in HEAs and their technological potential for maritime applications are presented and evaluated. Particular attention is devoted to prevailing preparation technologies, including powder metallurgy, vacuum arc melting, and additive manufacturing, and their influences on alloy integrity. Detailed analysis is provided for the corrosion resistance, biofouling resistance, cryogenic toughness, mechanical properties, wear resistance, and thermal stability of HEAs under marine service conditions. Prospects for their deployment in critical subsystems such as hull structures, propulsion systems, and functional coatings are assessed. Current findings indicate that synergistic optimization of compositional design, microstructural control, and advanced processing can enable HEAs to satisfy the extreme-environment performance requirements of marine structures. Nevertheless, the industrial translation of HEAs is presently hindered by common challenges: processing technologies that fall short of large-scale manufacturing demands and prohibitive alloy costs. Future research trajectories will concentrate on overcoming the bottlenecks in forming large-scale components and on balancing the performances and costs to accelerate the scalable implementation of HEAs in naval engineering.