The use of hybrid GFRP-timber composite structures has attracted extensive application over the past two decades. Accordingly, this paper investigates the structural behaviour of hybrid GFRP-timber girder by means of four-point bending tests carried out with various configurations. In the studied system, timber elements are connected to GFRP I-profiles by bolted shear connectors. Each homogeneous part of hybrid beams and hybrid beams themselves were first characterized within the elastic domain in torsion and bending, around major and minor axis. Torsional rigidities and bending stiffnesses were experimentally determined and showed the high gain provided by timber elements. Hybrid beams were finally tested in bending to failure. Measurements recorded during bending tests up to failure showed the different stages of flexural behaviour of these beams, and the resistance and failure modes were assessed. Test results showed that the load-carrying capacities of GFRP profiles were strongly increased as the timber beams were able to successfully delay the lateral buckling of the GFRP profiles. The importance of the contribution of timber beams depends on the section dimensions and materials properties. The presence of timber elements, even with low mechanical characteristics, allows to use the high mechanical performances of GFRP profiles.