This study aimed to comprehensively investigate the structure of purified exopolysaccharide EPS821-2, and the effect of Weissella cibaria FAFU821 on bread quality. Here, the findings determined that EPS821-2 was composed of 95.97 % glucose and 3.31 % mannose, with a molecular weight of 758.77 kDa. In addition, EPS821-2 was mainly composed of α-(1 → 6) linkages with branches containing α-(1 → 2), α-(1, 3 → 6), and α-(1, 4 → 6). Interestingly, EPS821-2 exhibited a three-dimensional structure, which led to the hypothesis that W. cibaria FAFU821 contributed to the quality of bread. The results revealed that W. cibaria FAFU821 enhanced the viscoelasticity of sourdough. It is remarkable that sourdough bread femented by W. cibaria FAFU821 had an excellent water holding capacity and lower hardness. In particular, W. cibaria FAFU821 increased the volatile profile of bread, including linoleic acid ethyl ester and acetic acid. This work provided the scientific insight for the applications of W. cibaria FAFU821 and its synthesized EPS821-2 in bakery innovation.