Phosphorus (P) is an essential macronutrient that plays a critical role in plant growth, development, and productivity. However, limited soil phosphorus availability can reduce crop performance in maize (Zea mays L.) and peanut (Arachis hypogaea L.). Native phosphate-solubilizing bacteria (PSB) convert insoluble P forms into plant-accessible forms. The aim of this study was to select efficient plant growth promotion native PSB to be used as a biological input in the development of sustainable biotechnological biofertilizers. For this, the effects of the inoculation of PSB isolates on maize and peanut’s phosphorus uptake, growth, and yield were evaluated. The assays were developed both under controlled greenhouse conditions and in field trials. Inoculation with native PSB strains significantly enhanced the plant growth and increased the phosphorus content of maize and peanut by 38–58% and 49.6%, respectively. These effects became evident earlier in the peanut than in maize. In field trials, inoculation with Serratia sp. S119 without chemical fertilizer application significantly increased maize yield. In conclusion, native PSB strains significantly promote plant growth, enhance phosphorus acquisition, and improve crop yield. The use of Serratia sp. S119 as a phosphate biofertilizer represents a promising strategy to reduce chemical fertilizer inputs and to promote more sustainable agricultural systems.