The combination of metal facesheets and solid composite core-based sandwich composite panels have appeared as the most suitable materials for automotive, shipbuilding, aeronautical and aerospace applications due to their superior flexural properties over traditional materials. However, there is a continuous need for further innovations to enhance their resistance to delamination, particularly in terms of their response to bending loads. One approach is incorporating 3D-woven fabric arrangements in the composite core materials into these structures. The present study involves an investigation of the flexural behaviour of metal-faced sandwich composite sandwich panels with unidirectional (UD), two-dimensional (2D) and three-dimensional (3D) woven fabric-reinforced polymer (FRP) composite cores. The objective is to understand and analyse the effect of core fabric design arrangement on the flexural performance of these composite panels. Flexural tests are performed to evaluate the flexural strength, flexural stiffness, energy absorption and failure modes of the tested panels. The results revealed that the core fabric reinforcement significantly influenced the flexural behaviour of the panels. The sandwich panels featuring a 3D fabric-reinforced core demonstrated superior performance in multiple aspects. They displayed the highest levels of flexural strength, specific flexural stiffness, specific energy absorption (SEA) and ultimate core shear strength among all the panels examined. These findings underscore the immense potential of employing 3D woven core-based sandwich structures, particularly in applications where superior flexural performance is a critical requirement.