<p>Green hydrogen, produced using renewable energy, is vital for achieving global decarbonization. Offshore wind energy, with its high efficiency and scalability, offers a promising pathway for cost-effective hydrogen production. The review systematically compares offshore and onshore renewable energy-driven hydrogen systems, highlighting the technical and economic challenges specific to marine environments, including corrosive seawater exposure, intermittent energy supply, and infrastructure scalability. This review also examines advancements in proton exchange membrane water electrolysis (PEMWE) technologies, particularly innovations in porous transport layers (PTLs), which are critical for managing mass transfer, conductivity, and durability in harsh marine environments. The development of perforated PTLs, such as SP-PTLs with corrosion-resistant coatings, significantly enhances performance, enabling stable operation in seawater conditions. Breakthroughs like dual-functional electrolysis that can simultaneously produce hydrogen and high-purity magnesium hydroxide, reduce costs by leveraging seawater’s mineral resources. The review concludes with a forward-looking perspective, emphasizing the urgency of developing low-cost PTLs, modular floating electrolyzer platforms, and policy frameworks to accelerate cost parity with fossil-derived hydrogen. By addressing these challenges, offshore hydrogen production can emerge as a linchpin of the net-zero transition, harmonizing technological advancement, economic viability, and environmental sustainability.</p>