Fibre Reinforced Polymer (FRP) rebars gained significant attention in recent years due to the advantages they offer over traditional reinforcement materials such as high resistance to corrosion, low density, and an excellent strength-to-weight ratio. Additionally, FRP rebars are non-conductive and non-magnetic, making them suitable for specialised applications where these properties are required. Despite these advantages, FRP rebars present also some drawbacks such as their linear elastic behaviour and low elastic modulus compared to steel, which results in limited ductility and increased deflections. In this context, hybrid systems combining steel and FRP rebars offer a solution by combining the high strength and corrosion resistance of FRP while benefiting from the ductility and stiffness of steel. This paper presents a finite element (FE) model of concrete beams reinforced with hybrid systems composed of FRP and steel rebars. The FE model was calibrated against experimental data from beams reinforced with different hybrid configurations. The ultimate load and deflection results obtained from the model demonstrated close agreement with experimental values. The results obtained confirm that the use of both FRP and steel rebars improves the flexural strength and ductility of the specimens (when compared to solely FRP reinforced beams). The validated FE model was subsequently used to carry out a parametric study on various beams with different concrete compressive strengths and hybrid reinforcement configurations. This study provides valuable insights into the flexural behaviour of concrete beams with hybrid FRP and steel rebars internal reinforcement, contributing to a deeper understanding of their mechanical performance under different conditions.