<p>A tungsten-doping strategy was developed to enhance the photocatalytic dye degradation and corrosion resistance of graphitic carbon nitride (CN). Using WCl₆ as a tungsten source, tungsten-doped CN (W-CN) was synthesized through a straightforward copolymerization process. Comprehensive characterization confirmed that tungsten ion incorporation modified the electronic band structure and disrupted local electron distribution, leading to extended visible light adsorption and improved separation and migration of photoexcited charge carriers. The resulting W-CN photocatalyst achieved a 5.14-fold increase in atrazine (ATZ) degradation rate. Additionally, the corrosion resistance of W-CN within waterborne polyurethane (WPU) coatings on metal substrates was evaluated. Enhanced hydrophobicity and a stronger physical barrier effect enabled the W-CN@WPU composite coating to significantly improve the corrosion resistance of Q235 carbon steel. This study demonstrates that tungsten doping not only boosts the photocatalytic degradation efficiency of organic pollutants by CN but also enhances the corrosion resistance of WPU coatings.</p>