Aquatic organisms can secrete biomacromolecules through specialized organs, tissues, or structures, enabling adhesion to underwater material surfaces and leading to severe biofouling issues. This phenomenon adversely impacts aquatic ecosystem health and human activities. Biofouling has emerged as an emerging global environmental challenge. Adhesion serves as the foundation of biofouling, representing a critical step toward a comprehensive understanding of the adhesion mechanisms of aquatic organisms. Biomacromolecules, including proteins, lipids, and carbohydrates, are the primary functional components in the adhesive substances of aquatic fouling organisms. Research indicates that these biomacromolecules exhibit diversity in types and characteristics across different aquatic organisms, yet their adhesion mechanisms show unifying features. Despite significant progress, there remains a lack of comprehensive reviews on the adhesion mechanisms mediated by biomacromolecules in aquatic fouling organisms, particularly on the roles of lipids and carbohydrates. Through a comprehensive analysis of existing literature, this review systematically summarizes the mechanistic roles of three classes of macromolecules in aquatic biofouling adhesion processes. Proteins demonstrate central functionality in interfacial adhesion and cohesion through specialized functional amino acids, conserved structural domains, and post-translational modifications. Lipids enhance structural stability via hydrophobic barrier formation and antioxidative protection mechanisms. Carbohydrates contribute to adhesion persistence through cohesive reinforcement and enzymatic resistance of adhesive matrices. Building upon these mechanisms, this review proposes four prospective research directions: optimization of protein-mediated adhesion functionality, elucidation of lipid participation in adhesion dynamics, systematic characterization of carbohydrate adhesion modalities, and investigation of macromolecular synergy in composite adhesive systems. The synthesized knowledge provides critical insights into underwater adhesion mechanisms of aquatic fouling organisms and establishes a theoretical foundation for developing mechanism-driven antifouling strategies. This work advances fundamental understanding of bioadhesion phenomena while offering practical guidance for next-generation antifouling technology development.