This study presents an efficient higher-order computational model to simulate delaminated fiber-reinforced polymer (FRP) composite beams. The approach utilizes a sub-laminate framework, dividing the multilayer structure into interconnected sub-laminates. Each sub-laminate, which may encompass multiple physical layers, incorporates cubic through-thickness variations for axial displacement and quadratic variations for transverse displacement. To capture these higher-order displacement fields, the model assigns variables at both the mid-plane and external surfaces of each sub-laminate. These surface variables enable seamless connectivity between adjacent sub-laminates in the thickness direction and explicitly simplify the modeling of delamination by accommodating displacement discontinuities. The framework allows users to balance accuracy and computational expense through customizable sub-laminate configurations, offering adaptability for diverse analysis needs. To improve computational efficiency, the model is integrated into a time-domain spectral finite element framework. Validation of the present model includes static bending, forced vibration, and wave propagation in composite beams, with results benchmarked against published datasets and commercial finite element software outputs. The comparisons demonstrate the model’s accuracy in predicting both static and dynamic behaviors while maintaining computational efficiency.