<p>This study investigated how different concentrations of oat <i>β</i>-glucan (OG) affected the structural and physicochemical characteristics of pea starch (PS). The results indicated that OG significantly influenced the gelatinization, structure, and digestibility of PS. From a structural perspective, although no new characteristic peaks appeared in the PS-OG samples compared to the PS gel, a reduction in particle size was observed. This indicated that OG interacted with the starch granules’ surface, preventing their expansion during gelatinization. Concerning the physicochemical properties, the incorporation of OG led to a reduction in both the peak and final viscosities of PS, while also increasing the pasting temperature. Moreover, OG inhibited amylose leaching from PS, resulting in a lower release of amylose and preventing its aggregation. This in turn reduced the short-term retrogradation of the starch. Additionally, OG decreased the in vitro digestibility of PS, enhancing its resistance to digestion, which could be advantageous for controlling blood sugar levels. This research explores the potential use of polysaccharide-starch complexes in functional food development, offering insights into their role in improving nutritional value.</p>