The novel synthesis of biohybrid nanocomposite [P. oxalicum/P2O5 + Ca3(PO4)2]BHC by Penicillium oxalicum in presence of tricalcium phosphate and phosphorus pentoxide for phosphate rocks. Phosphorus elemental solubilization from insoluble rock phosphate by utilizing microorganisms is a promising approach for lowering production costs and increasing environmental sustainability. P. oxalicum was isolated and identified in NRC, Cairo, Egypt, and proved its ability of P highest phosphate solubilization potential by estimating clear zone and solubilization index in Pikovskaya’s agar medium and available P and phosphatase enzyme in broth media. The highest dry shoot is the inoculation treatment P. oxalicum + Extract (52.59 g) in presence of TCP and the highest dry root is the inoculation treatment P. oxalicum (6.72 g) in presence of RP. The highest phosphate content and uptake are extremely in the presence of rock phosphate and tricalcium phosphate. the results showed that significantly increased the total counts of PSM at all sources of mineral phosphate fertilizer and PSF count is increased in presence of RP and TCP more than SSP compared with control. The biohybrid nanocomposite showed an absorbance of 0.26 and 2.23 at the wavelength (λ) 378 nm and 465 nm. Also, significant changes in the absorption index and indirect/direct bandgap of the biohybrid nanocomposite have been detected. To perform frequency calculations for crystal models and isolated molecules and optimize the molecular structure, the materials Studio 7.0 program using TDDFT/DMol3 and CASTEP methodologies were utilized. The DFT-Gaussian09W-vibration values are quite similar to the experimental data either in the structure or in the optical properties.