Biofouling remains a critical challenge across marine, medical, and industrial sectors, driving the need for sustainable and eco-friendly antifouling coatings. Biomass-based materials, including lignin, tannins, betaines, polysaccharides, and proteins, have emerged as promising candidates due to their biocompatibility, biodegradability, and diverse antifouling mechanisms. These materials inhibit biofouling through mechanisms such as hydration layer formation, surface charge repulsion, hydrophobic foul-release, and biocidal effects, offering effective resistance to protein adsorption, bacterial attachment, and biofilm formation. This review provides a comprehensive overview of recent advancements in biomass-based antifouling coatings, focusing on their antifouling mechanisms, synthesis methods, and applications. Key challenges concerning mechanical durability and scalability are explored, along with potential approaches to enhance the development of sustainable antifouling technologies.