Abstract: In this study, we investigated the effects of corn flour content, sea buckthorn pomace, yeast dosage, and fermentation time on the sensory evaluation of steamed bread. Based on single-factor sensory scoring, a Box-Behnken experimental design was employed to optimize the formulation of sea buckthorn pomace-corn flour-steamed bread. Analyses were conducted on the quality characteristics, antioxidant activity, in vitro digestibility, and simulated glycemic index of the optimized product while using steamed bread without sea buckthorn pomace as a control. The results demonstrated that the optimal formulation was 100 g of medium-gluten wheat flour supplemented with 44% corn flour, 4% sea buckthorn pomace, and 1.5% yeast and a fermentation time of 50 min. The sensory score of steamed bread prepared with this formulation was 97.10, closely matching the predicted value of 97.29. Sea buckthorn pomace significantly influenced the specific volume, texture, and flavor of steamed bread. The optimized product contained 0.033 mg/g polyphenols and 0.21 mg/g flavonoids, with DPPH and ABTS⁺ radical scavenging rates of 23.15% and 54.46%, respectively. In vitro digestion tests revealed that incorporating sea buckthorn pomace reduced both the glycemic index value and starch digestion rate, yielding an expected glycemic index (eGI) of 71.87, classifying it as a medium-GI food. This study provides a theoretical reference for applying sea buckthorn pomace to steamed bread products.