Siamenoside I is a rare mogroside in Siraitia grosvenorii Swingle and has become one of the target ingredients in natural sweetener production. However, the complex structure of siamenoside I has hindered its production in various ways. Here, a yeast cell that produces a specific β-glucosidase for siamenoside I conversion from mogroside V was constructed, and the enzymes were coelectrospun with poly(vinyl alcohol) followed by phenylboronic acid cross-linking to provide potential usage in the batch production process of Siamenoside I. A central composite design (CCD)-response surface methodology (RSM) was used to find the optimum coelectrospinning parameters. The pH stability and sodium dodecyl sulfate tolerance increased for the entrapped enzymes, and positive correlations between the fiber diameter and enzymatic activity were confirmed. The batch process showed an average siamenoside I production rate of 118 ± 0.08 mg L −1 h −1 per gram of fiber. This is the first research article showing specific siamenoside I production on enzyme-loaded electrospun fibers.