Nano α-alumina particles were synthesized by sol-gel method. Sodium dodecylbenzene sulfonate (SDBS) and sodium bis-2-ethylhexyl sulfosuccinate (Na (AOT)) were used as surfactant stabilizing agents. The prepared solution was stirred at different times (24, 36, 48, and 60 h) at 600 °C. Samples were then analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The finest particle size of range 20–30 nm was obtained at 48 h stirring time with SDBS surfactant at 1200 °C. Self-produced nano α-alumina particle was utilized to develop the α-alumina/polypropylene nanocomposite. Polypropylene (PP) matrix was filled and mixed with different weight percentages of α-alumina nanoparticles using a Haake internal mixer. Mixing was performed at 170 °C, and 50 rpm was set for the rotor speed. Tensile, flexural, and Izod impact tests were carried out. By adding 1–4 wt% of α-nano-alumina into PP matrix generated maximum tensile strength in both composites (~16% improvement contrasted to virgin PP), tensile modulus (~26–27% enhancement in both composite compared with virgin PP) and percentages of elongation at break in the range of 22–30% PP/nano α-Al2O3 composites without dispersant and with dispersant with addition of nano α-Al2O3 loading up to 5% in compared with virgin PP. Flexural analysis done to the PP/nano α-Al2O3 composites obtained a maximum of 50.5 and 55.88 MPa for flexural strength with the absence and presence of a dispersant, and flexural modulus is in the range of 1954–2818 MPa in both composites. Notched Izod impact energy showed an increasing pattern up to ~40–43 J/m for the PP/4 wt% nano α-Al2O3 composites in the absence and presence of a dispersant, before decreasing with further addition of filler loading.