Hard yellow maize is a crucial crop in Peruvian agriculture, playing a significant role in food security and livestock production. However, intensive fertilization practices in agronomic management have negatively impacted soil health. To explore more sustainable agricultural technologies, researchers have investigated using microorganisms to enhance plant growth. This study assessed the synergistic effects of microbial inoculants and mineral fertilization on INIA 619 and Dekal B-7088 maize varieties' yield and nutritional quality. A split-plot design was employed, incorporating four inoculation treatments—no inoculant, Bacillus subtilis, Trichoderma viride, and Pseudomonas putida—combined with fertilization levels of 0%, 50%, 75%, and 100%. The findings revealed that Bacillus subtilis boosted yields by 13.1% in INIA 619 and 55.5% in Dekal B-7088. Additionally, combined with 100% fertilization, microbial inoculation increased protein content by 47% and carbohydrates by 6% in INIA 619, while maintaining nutritional quality with 75% fertilization. Similarly, in Dekal B-7088, inoculation with total fertilization enhanced protein content by 54% and fiber by 27%. These results demonstrate that microbial inoculation can reduce mineral fertilization by up to 25% while sustaining high yields and improving the nutritional quality of maize.