The complexation of proteins with phenolic compounds has been considered a promising route to improve the oxidative stability of oil-in-water (O/W) emulsions. In this study, the physicochemical and functional properties of covalent complexes formed by sodium caseinate (SC) and quercetin (Q) were investigated. Different SC to quercetin molar ratios (1SC:0.1Q, 1SC:0.2Q, 1SC:0.5Q, and 1SC:1Q) were evaluated regarding their interaction under alkaline conditions. Formation of covalent complexes was analyzed by tracking changes in SC surface hydrophobicity and electrophoretic profile by SDS-PAGE, as well as characterization of zeta potential, size distribution, total phenolics and antioxidant activity of colloidal particles. The functionality of the complexes as emulsifier in O/W emulsions was analyzed by droplet size distribution, optical microscopy, kinetic stability (turbiscan) and lipid oxidation. Results showed that the hydrophobic surface of the SC decreased gradually upon increasing the concentration of quercetin. In addition, an increased antioxidant activity by DPPH and FRAP was observed at higher phenolic concentrations, as well as the ζ-potential showed a slight reduction in SC isoelectric point from 4.7 to 4.0. The SDS-PAGE analysis revealed the appearance of more intense bands at the top of the gel, depicting an increase in the molecular weight of the complexes compared to SC. Mean droplet size (D4.3) of the emulsion stabilized by complexes 1SC:1Q was slightly smaller than the one stabilized by SC, 1.632±0.068 and 1.809±0.299 µm, respectively. Kinetic stability results revealed a pronounced serum phase formation in all emulsions within 28 days. When analyzing lipid oxidation behavior, the formation of peroxides was higher in complexes with a lower amount of quercetin. However, the higher concentration of quercetin produced an emulsion with greater oxidative stability than the emulsion stabilized solely by SC. These results suggest that quercetin modification is a potential method for improving the functional properties of SC.