This chapter delves into the development and characterization of innovative nanocomposites made from DOPO (9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide) and phosphorus tetraglycidyl epoxy for aerospace use. The research addresses the urgent need for advanced materials with improved fire resistance and mechanical properties in aerospace engineering. It starts by explaining the synthesis of phosphorus tetraglycidyl epoxy resin and its modification with DOPO flame retardant additives. Comprehensive characterization of these materials is performed using Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and thermogravimetric analysis (TGA) to reveal the structural changes and interactions within the nanocomposite system. The chapter then assesses the fire retardancy and thermal stability of the nanocomposites through cone calorimetry and differential scanning calorimetry (DSC), showing promising results with reduced flammability and enhanced thermal resistance compared to traditional epoxy resins. Mechanical tests, including tensile, flexural, and impact assessments, indicate that incorporating DOPO and phosphorus tetraglycidyl epoxy significantly boosts the nanocomposites’ mechanical performance, making them viable for structural aerospace applications. In conclusion, this chapter not only demonstrates the successful synthesis and characterization of DOPO-based phosphorus tetraglycidyl epoxy nanocomposites but also highlights their potential as advanced materials for improving safety and performance in aerospace applications.