Introducing Pseudomonas putida optimizes the microbial community within the casing layer, thereby enhancing Agaricus bisporus growth. Nevertheless, the underlying mechanisms governing microbial community succession within the casing layer following microbial agent introduction remained elusive. This study delineated the interplay among microbial populations in the casing layer across the growth cycle of A. bisporus, comparing cohorts treated with P. putida (AP) against untreated controls (CK). The inoculation with Pseudomonas promoted the growth of A. bisporus, shortened its growth cycle, and linearly enhanced the relative abundance of key bacterial genera integral to its growth, including Flavobacterium, Rhodoferax, Pseudarthrobacter, and Vogesella (adjusted R2=0.238-0.866). Importantly, a positive correlation was identified between the proliferation of these beneficial bacteria and positive community cohesion (adjusted R2=0.353-0.838). Additionally, analysis of the symbiotic network topology within the AP group indicated a more stable community following inoculation. The niche results (AP=11.7672±1.8938, CK=11.0481±3.1273, P<0.05) underscored the positive impact of Pseudomonas inoculation on ecosystem dynamics. Concentrations of essential nutrients for A. bisporus growth, notably readily available phosphorus (On day 17, the AP group was 78.8333±1.26623 mg/kg, while the CK group was 30.0333±0.98658 mg/kg) and readily available potassium (On day 17, the AP group was 2693.9±14.79561 mg/kg, while the CK group was 1646.9333±10.71276mg/kg), were significantly elevated in the AP group. These enhancements strongly correlated with the increased abundance of pivotal microbial populations. Our research provided insights into the application of microbial inoculants to enhance the production of edible fungi.