<p>Anthocyanins (ACNs) are natural pigments with potent antioxidant activity, but their application in functional foods is restricted by their instability against heat and light. In this study, mung bean porous starch (PS) was prepared via ultrasound-assisted ethanol exchange at different ultrasonic powers and used as a wall material for ACN encapsulation, resulting in the formation of a PS@ACN composite system. The adsorption mechanism and stability enhancement were systematically investigated. The results showed that ultrasonic treatment significantly enhanced the adsorption capacity of PS, with the maximum loading capacity of 4.91&#xa0;mg·g⁻¹ obtained at 240 W. The suitability of the pseudo-first-order kinetic framework for describing the adsorption behavior suggested a predominantly physical adsorption pathway. Multiscale characterization showed that ultrasonic cavitation increased the specific surface area and pore volume at the macroscopic level. At the microscopic level, ultrasonic treatment disrupted the short-range ordered structure of starch and exposed more hydroxyl groups as potential binding sites. Molecular docking results suggested that hydrogen bonding was the primary driving force for the adsorption. Furthermore, the encapsulation significantly enhanced the stability of ACN, with the retention rate increasing with ultrasonic power. Under extreme thermal treatment (100&#xa0;°C), the stability of PS@ACN was improved by at least 1.5 times compared to free ACN. In vitro digestion experiments further showed that PS-240@ACN offered superior gastrointestinal protection and intestinal-responsive release. This study suggests that ultrasound-modified PS, especially at 240 W, may serve as a promising protective carrier for ACN.</p>