The increasing demand for sustainable offshore energy solutions necessitates efficient power conversion technologies that minimize environmental impact while ensuring reliable energy delivery. The DC-DC buck converter plays a crucial role in marine renewable energy systems, optimizing power conversion for offshore wind, wave, and floating solar applications. However, selecting the most efficient and sustainable converter requires balancing efficiency, reliability, cost, thermal performance, and size under harsh marine conditions. This study proposes a hybrid AHP-VIKOR methodology to evaluate and rank DC-DC buck converter designs, integrating expert-driven weighting (AHP) with quantitative ranking (VIKOR). The results identify the most optimal design, achieving high efficiency, minimal thermal losses, and improved durability, thus contributing to the sustainability of offshore energy systems. This approach systematically addresses multi-criteria trade-offs, ensuring a data-driven and environmentally conscious selection process. It supports the development of resilient, energy-efficient marine power electronics.