As the automotive industry focuses on fuel-efficient and eco-friendly vehicles along with reducing the carbon footprint, weight reduction becomes essential. Composite materials offer several advantages over metals, including lighter weight, corrosion resistance, low maintenance, longer lifespan, and the ability to customize their strength and stiffness according to specific loading requirements. This paper describes the design and development of the Rear Under Run Protection Device (RUPD) using composite materials. RUPD is designed to prevent rear under-running of passenger vehicles by heavy-duty trucks in the event of a crash. The structural strength and integrity of RUPD assembly are evaluated by applying loads and constraints in accordance with IS 14812:2005. The design objective was to reduce weight while maintaining a balance between strength, stiffness, weight, manufacturability, and cost. The process involved detailed laminate design, finite element analysis, and optimization using Altair Radioss and OptiStruct solvers. The layup configuration was designed to apply the pultrusion manufacturing process to it, which is well-suited for applications requiring a constant cross-section and high production rates. This technique offers a more efficient and cost-effective solution. Pultruded laminates are created by aligning rovings along the major axis of the component, while different continuous strand mats and fabrics are used to provide strength in the cross or transverse direction. The coupon tests were performed on various layup configurations to characterize the material in different directions for failure analysis material models. The design undergoes validation and optimization through quasi-static analysis, considering all load cases according to the standard. After finalizing the design through simulation, a final prototype was made based on the final laminate thickness, and the component was manufactured using the pultrusion manufacturing process. As a result, the weight of the newly designed RUPD was reduced by 25% compared to the previous metal component.