Structural Insulated Panels (SIPs) are widely used in residential, commercial, and bridge construction as wall, floor, or roof elements. However, existing SIPs suffer from inherent weaknesses such as insufficient load-bearing capacity, poor ductility, and susceptibility to cracking under flexural loading, limiting their broader application. To mitigate these drawbacks, presents study propose a novel SIP system featuring external hybrid face sheets comprised of Ultra-High-Performance Concrete (UHPC) and Carbon Fibre Reinforced Polymer (CFRP) and an expanded polystyrene (EPS) core reinforced with CFRP tube shear connectors. A detailed parametric study is conducted to investigate the effects of face sheet thickness, shear connector cross-sectional area and geometry, and shear connector layout on the flexural performance of the proposed SIP system. A commercially available finite element package ABAQUS is used to develop a detailed non-linear finite element model of the novel SIP. The concrete damage plasticity and orthotropic elasticity coupled with Hashin’s failure criteria are used to define the constitutive behaviour of the UHPC and CFRP, respectively. The study has been found that increased face sheet thickness and shear connector cross-sectional area enhance flexural performance of novel SIP system. Furthermore, circular shear connectors outperform square connectors, and non-uniform layouts with increased shear connector density near the SIP span ends improve its structural performance when compared to uniform layouts. The present study leads to a better understanding of the effect of geometric parameters related to the face sheet and shear connectors on the flexural performance and provides an understanding on providing an optimum deign for the novel SIP system.