Fungal mycelium is rapidly emerging as a next-generation food ingredient due to its high fiber and protein content, efficient upcycling of agro-industrial waste, and low environmental impact. In this study, we investigated for the first time the role of in-situ produced dextran in modulating the texture and digestibility of high-fiber bread formulated from a 50:50 blend of Cordyceps sinensis mycelium and wheat flour. We compared two structurally distinct dextrans, high molecular weight and linear structure from Weissella confusa VIII40, and lower molecular weight and highly branched structure from Pediococcus beninensis DSM 22752. Our findings demonstrate that fermentation with W. confusa VIII40 yielded 4.9% (dw) dextran, which significantly improved loaf specific volume, reduced crumb hardness, and delayed staling compared to control, effects not observed with dextran (2.22% dw) from P. beninensis DSM 22752 . In-situ produced dextran from W. confusa VIII40 significantly enhanced the bread’s nutritional profile, increasing DPPH radical scavenging activity and bile acid binding activity, while lowering the starch hydrolysis index (HI) and estimated glycemic index (eGI). These effects were linked to partial fiber solubilization and increases in digesta viscosity (2.6-fold) and particle size (1.6-fold) during intestinal digestion. Overall, integrating C. sinensis mycelium with in-situ dextran production via fermentation presents a promising strategy for developing clean-label, high-fiber functional breads with improved texture and health-promoting properties