In the present study, the impact behaviour of a hybrid beam consisting of a rectangular hollow GFRP pultruded profile filled with concrete is studied. The hollow pultruded GFRP box profile not only provides tensile strength but also protects the concrete block inside from suffering chemical attacks. The concrete on the other hand provides the system with bulk size and structural stability. A series of beams were subjected to low-velocity impacts by using a high capacity drop weight machine. A nonlinear finite element model was developed and calibrated to analyse the failure of the beams. In particular, it was used to reveal the failure modes, the cracking pattern, and damage sequences within the concrete hidden inside the pultruded profile. The calibrated finite element model was subsequently used to analyse hybrid beams of similar size to prestressed concrete railway sleepers. The numerical simulations revealed that in terms of the maximum load, the hybrid beam outperforms the prestressed concrete sleeper. Indeed, if the proposed beam is to be used as a railway sleeper, it needs to display better or equal dynamic properties to existing railway sleepers.