Abstract: To develop a novel protein-polyphenol-based emulsion stabilizer, coconut protein isolate (CPI) was used as the model protein to investigate the effects of covalent conjugation with varying concentration (0.3~0.9 mmol/L) of gallic acid (GA) on its structural characteristics, interfacial behavior, and emulsifying properties. The results demonstrated that GA grafting significantly altered the secondary structure of CPI, the shift in the characteristic peak was observed. Meanwhile, the GA grafting increased the absolute value of the zeta potential, and reduced the intrinsic fluorescence intensity of CPI. Dissipation quartz crystal microbalance (QCM-D) and interfacial dilatational rheology results revealed that the GA-modified coconut protein (CPI-gallic acid conjugates, CPG) formed viscoelastic interfacial film at the oil-water interface, thereby enhancing the centrifugal stability of the emulsions. As GA concentration increased, the interfacial film formed by CPG became thicker, and the emulsions exhibited smaller and more uniformly distributed droplets with markedly improved stability. These findings provide both theoretical insights and practical guidance for the application of gallic acid in protein-polyphenol-based emulsion systems.