The degradation of metal surfaces due to corrosion and fouling presents significant challenges in industrial and marine environments, leading to increased maintenance costs and material failures. Traditional protective coatings often rely on synthetic polymers and toxic additives, raising environmental concerns and facing increasing regulatory constraints. In this study, kraft lignin—an abundant byproduct of the pulp and paper industry—is investigated as a key component in bio-based coatings designed to simultaneously inhibit corrosion and biofouling.Kraft lignin’s intrinsic antioxidant activity, metal chelation capability, and hydrophobic nature make it a promising candidate for protective barriers. Through fractionation techniques, its structure is refined by narrowing lignin’s heterogeneity, allowing for tailored formulations that enhance coating stability and performance.1 These bio-based treatments effectively reduce surface wettability and prevent microbial attachment—critical factors in mitigating both corrosion and fouling. 2 3To optimize the  best process of application and its versatility, different coating techniques—including bar coating, spin coating, and dip coating—were tested on various metal substrates such as Fe-based compounds, AISI 316 steel, AISI 304 steel, and aluminum.All lignin fractions were fully characterized via NMR spectroscopy (HSQC, HSQC0, 13C, 31P) and GPC analyses, providing a comprehensive overview of lignin structural features, including bonding patterns, hydroxyl group distributions, and molecular weight distributions. Additionally, DSC, contact angle measurements, and corrosion tests via electrochemical techniques demonstrated the effectiveness of these lignin-based coatings as a sustainable alternative to conventional protective systems. 4 5This research enhances high-performance, eco-friendly metal protection while highlighting the significant potential of lignin valorization for industrial applications.By integrating circular economy principles and reducing reliance on fossil-based materials, these findings pave the way for a new generation of sustainable coatings with significant environmental and economic benefits.