Beyond nutrition, taste quality is a key quality trait driving the global popularity of Agaricus bisporus. This study systematically investigated non-volatile taste-related metabolite dynamics in caps and stipes during fruiting body development using non-targeted metabolomics. Among 1358 identified metabolites (974 in caps, 997 in stipes), 328 taste-related metabolites were screened. Applying screening criteria of VIP > 1, p < 0.01, and fold change ≥ 2 or ≤ 0.5, 492 and 446 differentially accumulated metabolites (DAMs) were identified in cap and stipe during fruiting body development, respectively. Cross-tissue comparison revealed 975 tissue-specific DAMs between cap and stipe across all developmental stages. Notably, 127 and 116 taste-related DAMs in cap and stipe, respectively, exhibited seven distinct accumulation profiles. Key umami-related compounds, aroma precursors, and antioxidants peaked in cap tissue at stage 3 (closed cup stage), suggesting a preliminary optimal harvest timing for market-quality mushrooms based on metabolic profiling of non-volatile taste-active compounds. Organic acids and nucleotides were more abundant in immature stages, while phosphorylated six-carbon sugars showed stipe-dominant accumulation at middle–late stages. Notably, all taste-related conclusions are inferred from non-volatile metabolite characterization rather than direct sensory measurements. KEGG pathway enrichment highlighted that taste-related metabolites primarily shaped taste via amino acid biosynthesis, cofactor metabolism, lysine biosynthesis, and nucleotide pathways. These insights provide a metabolic foundation for optimizing cultivation strategies and enhancing product quality in Agaricus bisporus.