Background <p>Mineral-dissolving rhizobacteria are considered ecological friendly rhizonutrifying agents capable of promoting rhizospheric enzymatic activities, microbial biomass, and nutrient availability even under nutrient-deficient alkaline soil conditions. However, comprehensive studies on their effectiveness in calcareous soil are lacking. The current study hypothesized that beneficial rhizobacteria improve soil biochemical properties in calcareous soil through their impact on enzymatic activities, microbial biomass, and nutrient availability in the rhizosphere.</p> Methods <p>Rhizobacterial strains were isolated from wheat rhizosphere and characterized in vitro for their mineral solubilization potential, production of beneficial metabolites, and various enzymatic activities. A pot experiment was conducted to investigate the effect of sole and co-inoculation treatments on wheat growth, grain attributes, nutrient availability in soil and absorption in plants, soil enzymatic activities, and microbial biomass accumulation in wheat rhizosphere under calcareous soil conditions.</p> Results <p>The most effective mineral-dissolving rhizobacteria were identified as <i>Bacillus altitudinis</i> (strains SAM1, SAM7, SAM13, and SAM15) and <i>Bacillus cereus</i> (strain SAM9) through 16S rRNA partial gene sequencing. These strains demonstrated the dissolution of insoluble tricalcium phosphate, mica, zinc oxide, and manganese oxide, and promoted nutrient availability in the soil by producing organic acids. Inoculation enhanced wheat growth and grain development by promoting nutrient acquisition and stimulating rhizospheric microbial activity. Both sole and co-inoculation with rhizobacterial strains significantly increased soil enzymatic activities, microbial biomass carbon, nitrogen, and phosphorus, and nutrient availability in the wheat rhizosphere through organic matter decomposition. Among treatments, sole inoculation with <i>B</i>. <i>cereus</i> SAM9 and co-inoculation with <i>B. cereus</i> SAM9 + <i>B. altitudinis</i> SAM13 demonstrated the most dominant increase in wheat growth and grain attributes, nutrient availability in soil and absorption in plants, deposition of microbial biomass, and soil enzymatic activities.</p> Conclusions <p>The sole inoculation with <i>B</i>. <i>cereus</i> SAM9 and co-inoculation with <i>B. cereus</i> SAM9 + <i>B. altitudinis</i> SAM13 showed strong potential as bioinoculants for calcareous soils. These strains could be effectively integrated into commercial biofertilizer formulation as sustainable alternatives or supplements to chemical fertilizers, enhancing soil productivity and crop performance.</p> Graphical Abstract <p></p>