<p>This paper provides an in-depth study of the design and structural evaluation of a composite box beam for load-bearing uses. The goal is to enhance structural efficiency while reducing weight by optimising material choices and geometric design. Finite element analysis (FEA) was performed in ANSYS, exploring various fibre orientations and stacking sequences. The results show that composite box beams offer superior stiffness-to-weight ratios compared to traditional metal beams, with the best performance observed at a [0/45/90]ₛ layup. These insights offer valuable design guidelines for engineers working with composite structures in aerospace, automotive, and civil engineering fields.</p>