Bamboo is one of the very significant plants harvested or grown naturally in Ethiopia it can be used for the production of traditional and modern structural components for a variety of applications. Bamboo fiber-reinforced polymer fails due to various loading conditions, high water absorption, and high temperatures in application. As a result, improvement is required by adopting hybridization with synthetic fiber or filler to improve both physical and mechanical properties. This research aimed to determine the influences of different contents of waste chopped glass fiber (CGF) as a filler (0, 5, and 10 wt.%) on different contents of long unidirectional 0⁰ and randomly oriented short bamboo fiber (30, 35, and 40 wt.%) reinforced polyester composites manufactured using the hand layup method. Mechanical properties including tensile strength, flexural strength, and impact strength as well as physical properties like water absorption and thermal stability are investigated. The results revealed that all properties of bamboo fiber reinforced polyester with CGF filler composites are were found to be superior to those without CGF in both long unidirectional 0⁰ and randomly oriented short fiber. Unidirectional 0⁰ bamboo fiber weight of 40% and 5 % chopped glass fiber had the maximum ultimate tensile strength, flexural strength, impact strength, water absorption, and thermal stability of about 131.22 MPa, 128.76 MPa, 113.3 KJ 𝑚𝑚2 , 1.94%, and up to 255⁰C (or 10% improvement) respectively compared to unfilled. To determine the significance of variables, and interaction between variables and responses, the statistical analysis is also examined using the analysis of variance (ANOVA) and response surface methodology (RSM). According to the statistical analysis, both bamboo fiber and chopped glass fiber content are significant variables in all responses of both cases. all mechanical properties of long unidirectional bamboo fiber have a quadratic model, and water absorption is linear with a two-factor interaction model. However, the tensile, flexural, and water absorption models for randomly oriented short fiber are linear, while the impact energy model is quadratic. All of the models agreed well with the experimental results, indicating that they can provide better forecasting in all cases. Keywords: Bamboo Fiber, Chopped glass fiber, Mechanical Property, Physical property, RSM