This paper investigates the influence of stress-induced soil anisotropy on the Factor of Safety (FOS) of geosynthetic reinforced slopes, presenting both analytical derivations and real-case evaluations. The study focuses on deriving a comprehensive factor of safety expression for geosynthetic stabilized slopes, explicitly considering the effect of stress-induced soil anisotropy. The directional dependence of soil properties, particularly strength and shear resistance, is incorporated into the factor of safety formulation. The developed analytical solutions provide a robust framework for accurately predicting the stability of geosynthetic reinforced slopes under stress-induced anisotropic soil conditions. The paper applies the derived analytical solutions to evaluate the FOS for a real-case geosynthetic-stabilized slope in Taichung, Taiwan, which failed due to heavy rainfall and typhoon events. The analysis demonstrates a significant decrease in FOS when anisotropy is considered, with the anisotropic model yielding an average FOS of 0.52 compared to the conventional FOS of 1. This highlights the critical impact of anisotropy on slope stability and emphasizes the necessity of incorporating it into design and analysis to accurately predict and prevent slope failures. In summary, incorporating stress-induced soil anisotropy into slope stability analyses for geosynthetic reinforced slopes is crucial for precise predictions, aiding informed decisions in design, construction, and risk management. This study advances understanding of the complex relationship between stress-induced soil anisotropy and geosynthetic reinforcement, thereby facilitating the development of improved and sustainable slope stabilization strategies.