Frozen dough storage, along with its thawing process, negatively affects the quality of the final product. Thus, fermentation with selected cultures and the enrichment of wheat-based dough using a specific soy powder could optimize the viscoelastic quality of frozen dough and increase its nutritional characteristics. Based on these aspects, the present study's objective was to examine the effects of soy powder addition to wheat flour with single cultures of Fructilactobacillus florum DSM 22689 or Saccharomyces cerevisiae and coculture with these two microorganisms for 72 h of fermentation. Additionally, the fermentation process was monitored, and viscoelastic behavior and physical-chemical analyses of the fermented sourdough before and after frozen storage were assessed, as soy protein has been proposed to hinder water migration throughout frozen storage. As observed, soy powder, an essential functional ingredient, had a favorable impact on the water-starch-gluten system, and enhanced the viscoelastic behavior before and after 4 weeks of frozen storage.