<p>Flavonoids are of great value in the food industry, but they are prone to degradation during processing, storage, transportation, and gastrointestinal transit. Additionally, their low solubility in polar solvents results in poor absorption and low bioavailability. To address these challenges, encapsulation within protein–polysaccharide matrices has emerged as an effective strategy to improve the solubility, stability, and bioavailability of hydrophobic flavonoids. This paper systematically reviews recent advances in flavonoid–protein–polysaccharide composite systems (FPP). Key factors affecting encapsulation efficiency are discussed, including the sequence of ingredient incorporation, material properties, and the interfacial forces between proteins, flavonoids, and polysaccharides. The influence of various preparation methods on the structural and functional properties of ternary systems is also examined. Furthermore, the review highlights how ternary composites enhance emulsifying, film-forming, and gelling properties. Collectively, this work provides a theoretical foundation for the future development of flavonoid delivery systems.</p>