Bitterness in foods arises from diverse compounds and is influenced by food matrix composition. Developing naturally derived bitterness suppressors with broad applicability is important for improving food flavor quality. In this study, submerged fermentation of Lentinula edodes was employed as a biotransformation strategy to produce a bitterness blocker (BB), and its inhibitory effects on bitterness across different food systems were systematically evaluated. Fermentation conditions were first optimized using single-factor experiments combined with Box-Behnken response surface methodology. The bitterness-suppressing effects of BB were then assessed through static sensory evaluation, temporal sensory analysis, and instrumental taste measurements. The results showed that BB significantly suppressed bitterness in five food systems, including stevia, monk fruit, coffee, corn peptides, and limonin, with bitterness suppression rates ranging from 13.54% to 26.52% at the respective optimal BB concentrations (2-8 g·L-1). Temporal sensory analysis showed that BB reduced the dominance of bitterness and promoted the dominance of other sensory attributes during subsequent perception. Electronic tongue analysis revealed reductions of 9.04-17.72% in bitterness responses across the five systems, further supporting the broad-spectrum bitterness-suppressing effects of BB. Overall, BB exhibits promising bitterness-suppressing activity across diverse food systems, providing a potential approach for developing naturally derived, broad-spectrum bitterness suppressors through edible mushroom fermentation.