ABSTRACT Starch‐based foods are essential components of the human diet, with proteins playing a critical role in modulating their physicochemical properties and digestive behavior. However, current research lacks systematic comparisons of the differing impacts of proteins from various sources, endogenous versus exogenous, plant‐based versus animal‐derived, on the multiscale structure, functional attributes, and digestibility of starch. Furthermore, the synergistic mechanisms by which protein‐polyphenol, protein‐lipid, and protein‐polysaccharide ternary complexes influence starch functionality remain inadequately elucidated. This review synthesizes the structural foundations of protein‐starch interactions mediated by hydrogen bonding, electrostatic forces, hydrophobic associations, and covalent bonding. It provides a focused analysis of the regulatory roles and mechanisms of various proteins in starch gelatinization, retrogradation, swelling behavior, and enzyme‐mediated digestibility. In addition, this review comprehensively addresses the synergistic effects of protein‐polyphenol, protein‐lipid, and protein‐polysaccharide composite systems in the functional modification of starch. This work provides a theoretical foundation for the development of innovative starch‐protein composite foods with tailored nutritional functions and a reduced glycemic response.