Roselle cultivation in sandy soils faces major challenges like poor water and nutrient retention, negatively impacting plant growth and yield. This study aimed to evaluate the potential of microbial inoculants to improve roselle productivity in nutrient-deficient sandy soils. A field experiment was conducted in Egypt over two seasons using eight microbial treatments: Bacillus subtilis, Pseudomonas fluorescens, Pleurotus ostreatus, Mycorrhizeen (mycorrhizal) fungi, and combinations thereof, along with a non-inoculated control. Microbial inoculants were applied as seed treatment and soil drench to improve sandy soil fertility. All microbial inoculants significantly increased fresh and dry calyx yield, shoot growth, seed yield, and overall biomass versus the control. Bacillus subtilis gave the greatest enhancement in yield parameters. Combining Bacillus, Pseudomonas, Pleurotus and mycorrhizae led to further synergistic yield improvements up to 332% over control. Microbial inoculation also dramatically increased nitrogen and potassium uptake by up to 724% and utilization efficiency compared to control plants. Results demonstrate the excellent potential of microbial inoculants to significantly improve roselle productivity and nutrition in nutrient-deficient sandy soils through synergistic promotion of soil fertility and plant growth. Microbial inoculation could provide a sustainable solution to challenges of roselle cultivation in poor sandy soils.