Objective To improve the functional characteristics of egg white protein (EWP) by tagatose glycosylation.Methods Firstly, the differences in antioxidant activity, emulsifying property, emulsion stability, foaming ability, and foaming stability are compared among glycosylated EWP (G-EWP), heat-treated EWP (H-EWP), and EWP. Then, the mechanism underlying the structural changes of G-EWP is investigated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, Fourier transform infrared spectroscopy, circular dichroism, scanning electron microscopy, and particle size analysis.Results Compared with EWP and H-EWP, G-EWP exhibits significantly improved antioxidant activity, emulsifying property, emulsion stability, foaming ability, and foaming stability (P<0.05). After glycosylation, the molecular weight increases. Tagatose is covalently grafted to egg white protein, with the content of α-helix, β-sheet, and β-turn changing and the morphology changing from spherical to large block-like complexes. The average particle size decreases from 153.53 nm to 129.33 nm (P<0.05), and the zeta potential value decreases from -22.68 mV to -31.83 mV (P<0.05).Conclusion Tagatose glycosylation can significantly improve the functional characteristics of EWP.