This study aimed to investigate the differential binding affinities of various catechins to whey proteins and their subsequent impact effects on the proteins' digestive properties by selecting four catechins with distinct structural characteristics. The strengths of these interactions were evaluated using molecular docking, interaction force analysis, group content evaluation, and physicochemical property assessment. Additionally, the influence of catechin structures on the digestive properties and digestion products of the complexes was examined using an in vitro digestion model. The results demonstrated that an increase in hydroxyl and galloyl groups enhanced the interaction strength between catechins and whey proteins. Notably, epigallocatechin gallate exhibited the strongest interaction, achieving a binding rate of 90.56%. The catechins induced unfolding of the whey protein structure, exposing internal groups through the enhancement of hydrogen bonding and hydrophobic interactions, thereby facilitating the formation of complexes with reduced particle sizes. The digestive properties of these complexes were closely associated with the structural attributes of the catechins. As the number of galloyl and hydroxyl groups increased, the complexes exhibited improved digestibility and hydrolysis. This enhancement was attributed to the unfolding of the whey protein structure and a reduction in particle size. Consequently, the digested products contained a higher proportion of small peptides, with the proportion of peptides having molecular weights less than 1000 Da in the digested product of the epigallocatechin gallate-whey protein complex reaching 43.4%. Antioxidant activity analysis further indicated that the generation of small peptides enhanced the antioxidant activity of the digestion products. Therefore, catechins with a greater number of hydroxyl and galloyl groups facilitated stronger interactions with whey proteins, thereby promoting their digestion. This study provides theoretical insights for the development of milk-based tea beverages and the digestion processes of complex foods.