Lignin, a structurally complex aromatic polymer comprising 15–30% of woody plant biomass, plays a pivotal role in plant integrity and global carbon cycling. This section investigates the degradation of lignin and its oligomeric fragments by microorganisms, emphasizing the unique enzymatic systems adapted to the physicochemical challenges of marine environments. The structural heterogeneity of lignin complicates its valorization; however, marine bacteria have evolved specialized metabolic pathways that enable efficient processing under both aerobic and anaerobic conditions. Particular attention is given to key ligninolytic enzymes, including intracellular glutathione-S-transferases, which facilitate the conversion of lignin-derived compounds. The ecological significance of marine microbial communities in mediating lignin degradation and contributing to coastal and oceanic carbon dynamics is also addressed. Advances in molecular biology have revealed novel metabolic pathways and genetic architectures, offering promising avenues for biotechnological applications including the production of bio-based materials and bioplastics. As global interest in sustainable resource utilization intensifies, elucidating the metabolic potential of marine bacteria for lignin valorization is crucial for promoting environmental resilience and advancing a circular bioeconomy.