This study introduces Gum Arabic (GA), a natural polysaccharide, as an innovative bio-modifier for AP-5 asphalt cement, marking a step toward sustainable civil engineering materials. We investigated the effects of GA at varying concentrations (e.g., 5, 10, and 15 wt.%) using advanced analytical techniques such as Fourier-transform infrared spectroscopy (FT-IR), thin-layer chromatography-flame ionization detection (TLC-FID), and scanning electron microscopy (SEM). FT-IR analysis revealed GA's interaction with asphalt as primarily physical, suggesting its role as a stabilizing agent. TLC-FID results indicated a chemical shift in the asphalt composition, with a notable increase in saturates and resins and a decrease in aromatics, enhancing the asphalt’s thermodynamic stability. SEM analysis demonstrated excellent miscibility of GA with the asphalt binder, crucial for consistent material performance. Rheological tests revealed changes in the mechanical properties of the asphalt, including reduced penetration and ductility but increased softening point and viscosity. Dynamic shear rheometer (DSR) testing indicated improved rutting resistance, enhancing the asphalt's high-temperature performance. Our findings suggest that GA is an effective, environmentally friendly additive, offering significant improvements in asphalt mixture performance.